Check the orc's body.

You're about to have to head out into a dangerous dungeon. Given that you were left behind with the key to your cell within reach, your would-be savior can't have cleared out all the dangerous things in the place, even if he was successful enough to make it out alive himself. You don't want to head out empty-handed.

Looking over the orc's body, you see that it's hand clutches a heavy wooden club. There is a key ring with two keys on it's belt, and it's wearing some half-plate armor.

The keys seem like a no-brainier. It'd be simple enough to slide the metal circle over your arm and wear it like a bangle. The other items are a bit more iffy. You may not be a stranger to manual labor, but orcs are bigger and burlier, and that equipment may be a bit too heavy for you to use. Though it may be better than nothing all the same.