I don't remember ME being that long when we went to ASMu in Sept. Our flight landed at 10AM (20 minutes early) and a bus was there for the All-Stars. We waited maybe ten minutes to leave the airport and then there was the 45ish minute drive. Sports is the first stop, so you won't even have to wait for everyone else to get off the bus.
The check-in process was quick (no line), and since our room was ready, we dropped off our carry-on things.. if you're really in a rush you could maybe leave them with the bell-hop outside and get them when you come back.
The ride to MK from ASSp is probably 15 minutes or so, if you get there right when a bus shows up.