From http://www.epochconverter.com/
SELECT DATEDIFF(s, '1970-01-01 00:00:00', GETUTCDATE())
My bad, SELECT unix_timestamp(time) Time format: YYYY-MM-DD HH:MM:SS or YYMMDD or YYYYMMDD. More on using timestamps with MySQL:
http://www.epochconverter.com/programming/mysql-from-unixtime.php