Return the first entry in the delayed zset (a tuple with the job's pk
        and the score of the zset, which it's delayed time as a timestamp)
        Returns None if no delayed jobs

def first_delayed(self):
        """
        Return the first entry in the delayed zset (a tuple with the job's pk
        and the score of the zset, which it's delayed time as a timestamp)
        Returns None if no delayed jobs
        """
        entries = self.delayed.zrange(0, 0, withscores=True)
        return entries[0] if entries else None