It would absolutely not survive for very long like this (naked PCB on a key-chain). Mechanical damage from the actual keys on the same chain is what will kill it before water, sweat, washing liquid, pocket lint or ESD do.

First things to fail will be ceramic capacitors torn/cracked and leads of SSOP-20 package bent/shorted.

That said, it is trivial to protect the board from all of above - just wrap it (except USB connector) with insulating tape or better yet, cover with silicone putty, or similar.