diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 3c735fc0309b6..e431d0bcf7e9b 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -3100,20 +3100,16 @@ def _filter_indexer_tolerance(
     # --------------------------------------------------------------------
     # Indexer Conversion Methods
 
-    def _convert_scalar_indexer(self, key, kind=None):
+    def _convert_scalar_indexer(self, key, kind: str_t):
         """
         Convert a scalar indexer.
 
         Parameters
         ----------
         key : label of the slice bound
-        kind : {'loc', 'getitem', 'iloc'} or None
+        kind : {'loc', 'getitem'}
         """
-        assert kind in ["loc", "getitem", "iloc", None]
-
-        if kind == "iloc":
-            self._validate_indexer("positional", key, "iloc")
-            return key
+        assert kind in ["loc", "getitem"]
 
         if len(self) and not isinstance(self, ABCMultiIndex):
 
diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
index 2eda54ec8d4ed..85229c728848f 100644
--- a/pandas/core/indexes/category.py
+++ b/pandas/core/indexes/category.py
@@ -624,10 +624,11 @@ def get_indexer_non_unique(self, target):
         return ensure_platform_int(indexer), missing
 
     @Appender(Index._convert_scalar_indexer.__doc__)
-    def _convert_scalar_indexer(self, key, kind=None):
+    def _convert_scalar_indexer(self, key, kind: str):
+        assert kind in ["loc", "getitem"]
         if kind == "loc":
             try:
-                return self.categories._convert_scalar_indexer(key, kind=kind)
+                return self.categories._convert_scalar_indexer(key, kind="loc")
             except TypeError:
                 self._invalid_indexer("label", key)
         return super()._convert_scalar_indexer(key, kind=kind)
diff --git a/pandas/core/indexes/datetimelike.py b/pandas/core/indexes/datetimelike.py
index 13fb955c32832..b143ff0aa9c02 100644
--- a/pandas/core/indexes/datetimelike.py
+++ b/pandas/core/indexes/datetimelike.py
@@ -385,7 +385,7 @@ def _format_attrs(self):
     # --------------------------------------------------------------------
     # Indexing Methods
 
-    def _convert_scalar_indexer(self, key, kind=None):
+    def _convert_scalar_indexer(self, key, kind: str):
         """
         We don't allow integer or float indexing on datetime-like when using
         loc.
@@ -393,10 +393,10 @@ def _convert_scalar_indexer(self, key, kind=None):
         Parameters
         ----------
         key : label of the slice bound
-        kind : {'loc', 'getitem', 'iloc'} or None
+        kind : {'loc', 'getitem'}
         """
 
-        assert kind in ["loc", "getitem", "iloc", None]
+        assert kind in ["loc", "getitem"]
 
         if not is_scalar(key):
             raise TypeError(key)
diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 9ec72df140c85..03fb8db2e1e1e 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -529,9 +529,9 @@ def _should_fallback_to_positional(self):
         return self.dtype.subtype.kind in ["m", "M"]
 
     @Appender(Index._convert_scalar_indexer.__doc__)
-    def _convert_scalar_indexer(self, key, kind=None):
-        if kind == "iloc":
-            return super()._convert_scalar_indexer(key, kind=kind)
+    def _convert_scalar_indexer(self, key, kind: str):
+        assert kind in ["getitem", "loc"]
+        # never iloc, so no-op
         return key
 
     def _maybe_cast_slice_bound(self, label, side, kind):
diff --git a/pandas/core/indexes/numeric.py b/pandas/core/indexes/numeric.py
index 2f4c48cc2e5a5..d67c40a78d807 100644
--- a/pandas/core/indexes/numeric.py
+++ b/pandas/core/indexes/numeric.py
@@ -250,12 +250,11 @@ def asi8(self) -> np.ndarray:
         return self.values.view(self._default_dtype)
 
     @Appender(Index._convert_scalar_indexer.__doc__)
-    def _convert_scalar_indexer(self, key, kind=None):
-        assert kind in ["loc", "getitem", "iloc", None]
+    def _convert_scalar_indexer(self, key, kind: str):
+        assert kind in ["loc", "getitem"]
 
-        # don't coerce ilocs to integers
-        if kind != "iloc":
-            key = self._maybe_cast_indexer(key)
+        # never iloc, which we don't coerce to integers
+        key = self._maybe_cast_indexer(key)
         return super()._convert_scalar_indexer(key, kind=kind)
 
 
@@ -388,12 +387,9 @@ def _should_fallback_to_positional(self):
         return False
 
     @Appender(Index._convert_scalar_indexer.__doc__)
-    def _convert_scalar_indexer(self, key, kind=None):
-        assert kind in ["loc", "getitem", "iloc", None]
-
-        if kind == "iloc":
-            self._validate_indexer("positional", key, "iloc")
-
+    def _convert_scalar_indexer(self, key, kind: str):
+        assert kind in ["loc", "getitem"]
+        # no-op for non-iloc
         return key
 
     @Appender(Index._convert_slice_indexer.__doc__)
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index f55a54a54d0d7..bf42cf0330ef0 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2033,7 +2033,8 @@ def _convert_to_indexer(self, key, axis: int, is_setter: bool = False):
             return labels._convert_slice_indexer(key, kind="iloc")
 
         elif is_float(key):
-            return labels._convert_scalar_indexer(key, kind="iloc")
+            labels._validate_indexer("positional", key, "iloc")
+            return key
 
         self._validate_key(key, axis)
         return key