It exists and is 'open' past 5-6 pm. Sometimes late at night (i.e. 10-11 pm) they stop enforcing it as an elite/premium entry, but they keep it open.

Generally it is right of the elevator (facing the ticket counter) by where the QF check-in is. Occasionally they will use the escalator to the left of the elevator by where all the kiosks are. It is only a premium lane until you get to the ID checker, then it merges with the regular security area, but depending on how busy it is you may save some time.