I am trying to setup celery worker for my new superset installation. I have set the database in Async query execution , but my queries keep going in pending state. Anything I am missing here?\n\nCelery start up cmd - `celery worker --app=superset.tasks.celery_app:app --pool=prefork -O fair -c 4`\n\nMy config is\n```import os\nSUPERSET_CONFIG_PATH = '/etc/superset/superset_config.py'\nRESULTS_BACKEND = 'mysql+mysqlconnector://user@default..com/superset'\n\nROW_LIMIT = 200000\nSUPERSET_WORKERS = 4\nSUPERSET_WEBSERVER_PORT = 8080\nSECRET_KEY = 'mykey'\nSQLALCHEMY_DATABASE_URI = 'mysql+mysqlconnector://user@com/superset'\nCSRF_ENABLED = True\nLANGUAGES = {"en": {"flag": "us", "name": "English"} }\n\nclass CeleryConfig(object):\n    BROKER_URL = 'redis://localhost:6379/1'\n    CELERY_IMPORTS = ('superset.sql_lab', 'superset.tasks',)\n    CELERY_RESULT_BACKEND = 'redis://localhost:6379/1'\n    CELERYD_LOG_LEVEL = 'DEBUG'\n    CELERYD_PREFETCH_MULTIPLIER = 1\n    CELERY_ACKS_LATE = True\n    CELERY_ANNOTATIONS = {\n        'tasks.add': {\n            'rate_limit': '10/s'\n        },\n        'sql_lab.get_sql_results': {\n            'rate_limit': '100/s'\n        }\n    }\n    CELERY_TASK_PROTOCOL = 1\nCELERY_CONFIG = CeleryConfig\n\nfrom cachelib.redis import RedisCache\nRESULTS_BACKEND = RedisCache(\nhost='localhost', port=6379, key_prefix='superset_results')```