I'd remove it from its case. The easiest and cheapest thing would be to let it dry out for a day or two before turning it on, then see if any problems develop. If there are any problems then make an appointment at a Genius Bar. It is possible there aren't any problems and you were lucky (I know somebody who dropped their phone in water for 2 seconds and it still works a year later).
Genius Bar appointment - Unfortunately Apple has made this difficult to get to directly. Go to https://www.apple.com/retail/geniusbar/ > Get hardware help. Select your hardware and continue selecting options requiring replacing parts until you see "Bring in for Repair" --> Sign in with Apple ID
How to find your nearest Apple Authorized Service Provider (AASP) or Apple Authorized Distributor (AAD) - https://locate.apple.com/country or see if you can find any service locations in https://locate.apple.com/findlocations Some places with limited support may be included in the "other" link at the bottom of a region selection.