How long does apple take to fix a ipod touch 4g

i recently just dropped my ipod in water by accident, and everything seems fine after i did the rice method with it. the only problem now is the "volume up" button and the lock button rnt exactly working. Volume up doesnt do anything, and pressing the lock screen increases the volume fully. without even locking the ipod. Im using the touch thing right now, but there's a new apple store near where i live now. i was wondering if apple could fix the lock button, and volume up button. and is that section under warranty? cause my ipod is still under warranty. And how long do you think they would take to fix it?