Chest with Midden Maw Key

[Dorok]

After have finished the area (which ended with a forced red combat which is rather weird when the game stuck you with no exit to grind, but playable anyway) I searched for hidden stuff not yet found, that is hints of doors and hidden buttons to find.

I ended with one area hinted on map and no clue how reach but ok give up. And a chest in a hidden area but requiring a Midden Maw Key.

Except that I remind have found 2 keys but had to use them. Any idea where is this third key?

Or is it at alternate path not opening a door with the key and then has it for the chest?

[ebbpp]

Same problem, got all secrets, but not enough keys for the chest :/

[Kalter Stahl]

I think this chest is typo'd, after searching for like an hour I considered this theory and made a simple lockpick... and it unlocked lol.

[Halcyon Cousland]

Thank you so much Kalter, I spent 15 mins and I was 99.99% confident I hadn't missed anything in the dungeon... typo it is, normal Lockpick it is... frustrating but solved <3