Arriving in Beijing by Air Asia D7 312 at 04:40AM

Hello, Moloy. Your time is enough for transfer. You should follow these procedures t go:
Flight Arrival - Inspection & Quarantine, Exit and Entry Frontier Inspection - Customs Inspection - Baggage Claim - Going through Transfer Formalities - Waiting & Boarding

You will arrive at T2, but the departure terminal is unknown without the flight no. Anyway, if it is need to travel between terminals, the free shuttle bus will help.