@classmethod
def get_by_auth_token(cls, user_id, token):
    """Returns a user object based on a user ID and token.

        :param user_id:
            The user_id of the requesting user.
        :param token:
            The token string to be verified.
        :returns:
            A tuple ``(User, timestamp)``, with a user object and
            the token timestamp, or ``(None, None)`` if both were not found.
        """
