What a bloody mess! Looks like someone was trying to pound the door down with their bloody fist. You try the handle but the door is locked. Are you going to try the other key you found or go back down the tunnel?

Actually, I would like to put our ear to the non-bloodiest portion of the door and try to listen to the other side. Yes, we should try the other key, but do NOT open it yet if it works.

Trying to be cautious you press your ear to the door.....silence.....nothing but silence. You do notice that the blood, although long dried, still appears deep red in appearance. You press the key into the slot and turn. The door is now unlocked. Now do you want to open the door with some type of weapon at the ready?

my vote is that our bystander will decide this next move . . . i'd probably end up killing us

Definitely a crowbar in our strong hand, and we'll open the door keeping our back to it like a shield.

p.s. Thanks for the nomination.