diff --git a/doc/source/whatsnew/v2.2.1.rst b/doc/source/whatsnew/v2.2.1.rst
index 310dd921e44f6..ce2c54668ed61 100644
--- a/doc/source/whatsnew/v2.2.1.rst
+++ b/doc/source/whatsnew/v2.2.1.rst
@@ -62,6 +62,7 @@ Bug fixes
 - Fixed bug in :func:`pandas.api.interchange.from_dataframe` which wasn't converting columns names to strings (:issue:`55069`)
 - Fixed bug in :meth:`DataFrame.__getitem__` for empty :class:`DataFrame` with Copy-on-Write enabled (:issue:`57130`)
 - Fixed bug in :meth:`PeriodIndex.asfreq` which was silently converting frequencies which are not supported as period frequencies instead of raising an error (:issue:`56945`)
+- Fixed bug in :meth:`_LocIndexer._convert_to_indexer` which doesn't properly insert timestamps into Series (:issue:`57596`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_221.other:
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index c7a938dbc4449..ef06ebdbb96a6 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -1490,7 +1490,10 @@ def _convert_to_indexer(self, key, axis: AxisInt):
 
             # if we are a label return me
             try:
-                return labels.get_loc(key)
+                label = labels.get_loc(key)
+                if label:
+                    return label
+                return {"key": key}
             except LookupError:
                 if isinstance(key, tuple) and isinstance(labels, MultiIndex):
                     if len(key) == labels.nlevels: