I am not an EK flyer, but I believe that there was a consensus on TG forum, that the only lounge at BKK airport, open 24h is Louis Tavern. You can gain access (for free) by showing Diners Club card (in theory only for 3h - but in practice no-one cares).
BTW.. you really want to stay at the airport


Go to the downtown area, book a decent hotel and - if you are really feed up with Bangkok downtown - spend the morning in the hotel's swimming pool or spa. BKK downtown hotels are much more affordable, than KUL Golden Triangle..