Fix tests and functionality of get_access_key_last_used()

moto/iam/responses.py

@@ -455,15 +455,13 @@ class IamResponse(BaseResponse):
         return template.render(name='UpdateAccessKey')
 
     def get_access_key_last_used(self):
-        user_name = self._get_param('UserName')
         access_key_id = self._get_param('AccessKeyId')
-        iam_backend.get_access_key_last_used(user_name, access_key_id)
-        template = self.response_template(GENERIC_EMPTY_TEMPLATE)
-        return template.render(name='GetAccessKeyLastUsed')
+        last_used_response = iam_backend.get_access_key_last_used(access_key_id)
+        template = self.response_template(GET_ACCESS_KEY_LAST_USED_TEMPLATE)
+        return template.render(user_name=last_used_response["user_name"], last_used=last_used_response["last_used"])
 
     def list_access_keys(self):
         user_name = self._get_param('UserName')
-
         keys = iam_backend.get_all_access_keys(user_name)
         template = self.response_template(LIST_ACCESS_KEYS_TEMPLATE)
         return template.render(user_name=user_name, keys=keys)
@@ -1247,6 +1245,18 @@ LIST_ACCESS_KEYS_TEMPLATE = """<ListAccessKeysResponse>
    </ResponseMetadata>
 </ListAccessKeysResponse>"""
 
+
+GET_ACCESS_KEY_LAST_USED_TEMPLATE = """
+<GetAccessKeyLastUsedResponse>
+    <GetAccessKeyLastUsedResult>
+        <UserName>{{ user_name }}</UserName>
+        <AccessKeyLastUsed>
+            <LastUsedDate>{{ last_used }}</LastUsedDate>
+        </AccessKeyLastUsed>
+    </GetAccessKeyLastUsedResult>
+</GetAccessKeyLastUsedResponse>
+"""
+
 CREDENTIAL_REPORT_GENERATING = """
 <GenerateCredentialReportResponse>
     <GenerateCredentialReportResult>