async def METHOD_NAME(user_id):
    with plugins.runtime.DB as db:
        try:
            user_id = int(user_id)
            return mk_user_key(user_id)
        except ValueError:
            user_key = await db.hash_get(DefaultAuthHandler.USER_INDEX_KEY, user_id)
            if user_key is None:
                return None
            return user_key if await db.get(user_key) is not None else None