SELECT destination
    FROM
        (SELECT destination, email, wildcard, localpart FROM alias
            UNION
             SELECT email AS destination, email, 0 AS wildcard, localpart FROM USER)
    WHERE
    (
     wildcard = 0
     AND
     email = '%s'
    ) OR (
     wildcard = 1
     AND
     '%s' LIKE email
    )
  ORDER BY
    wildcard ASC,
    LENGTH(localpart) DESC
  LIMIT 1