1) what is the flight arrival time at KLIA and then departure time at KLIA2.
2) With checked in luggage? How long did you have to wait for your checked in luggage to appear? KLIA bags take at least 20 minutes from landing to when the first bags appear on the belt.
3) Which gate were you parked at on arrival (KLIA) and which gate were you parked at for departure (KLIA2)
4) If you had never flown to KLIA before or used the train from KLIA to KLIA2 and then to navigate from the arrival hall and to locate the lift's (good luck trying to get into the lift's with a large volume of bags) going down to the train level and then to go back up at KLIA by lifts and to push your bags up to the Air Asia departure counters to firstly get your boarding pass from the machine if you have not checked in online yet, and then to line up to drop off your bags (I have never had a straight walk through to drop by bags...it was always a 15-30 minute line waiting to drop off my bags).
5) The walk from departure area through immigration, security and to the gates depending on WHICH GATES....

I am saying for a newbie who has never done a trip from KLIA to KLIA 2, it is impossible to do it in 40 minutes from gate to gate.