diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
index f7fead0d94dfe6..73408ae2037248 100644
--- a/pandas/core/indexes/category.py
+++ b/pandas/core/indexes/category.py
@@ -326,16 +326,18 @@ def __contains__(self, key):
         hash(key)
         if isna(key):
             return self.isna().any()
-        elif self.categories._defer_to_indexing:  # e.g. Interval values
+        try:
             loc = self.categories.get_loc(key)
-            return np.isin(self.codes, loc).any()
-        elif key in self.categories:
-            return self.categories.get_loc(key) in self._engine
-        else:
+        except KeyError:
             return False
+        if is_scalar(loc):
+            return loc in self._engine
+        else:  # if self.categories is IntervalIndex, loc is an array
+            return any(loc_ in self._engine for loc_ in loc)
 
     @Appender(_index_shared_docs['contains'] % _index_doc_kwargs)
     def contains(self, key):
+        hash(key)
         return key in self
 
     def __array__(self, dtype=None):