'Gets the expiration time for a given subject.'

@utils.Synchronized
def GetLock(self, subject):

    subject = utils.SmartStr(subject)
    query = 'SELECT    expires,    token    FROM    lock    WHERE    subject    =    ?'
    args = (subject,)
    data = self.Execute(query, args).fetchone()
    if data:
        return (data[0], data[1])
    else:
        return (None, None)
