-Keycards spawn in random places right when roles are declared.
-Every deck has a chance of spawning one or two keycards. If two have been found on one deck, you won't find any more there.
-Keycards may be holstered in your shoulder holsters, just like gadgets. Remember, you have TWO slots!

All possible spawn locations:

HANGAR DECK:
-airlock
-crate with laptop
-tall crate on the other side of hangar near engineering lift
-cargo hold - ontop of one of the crates, could be lower or upper level, but either spawn will be to your right when you enter through big door

DECK 2:
-desk of sick bay
-desk of office next to reactor
-atop one of the crates in the hall near airlock
-airlock (watch your back when you go for this one!)
-ontop of one of the crates in the room between main lift and door to reactor core
-on the upper walkway that goes around the reactor

DECK 3:
-the desk of any of the crew quarters
-the toilet in the streamers' quarters
-the TV table in the laundry room
-mess hall: either in the microwave, on the right side of the bar counter, or on the table of the VIP lounge upstairs