If I remember it right, that key is well hidden under some barrels/crates, so if you smash them all into pieces, you will see the key is lying there ... No ? smirk
But it's already a long time ago when I was there ::-p ... this rpg has a loooooong playtime, very long !
I'm now busy with the FoV part ... wink

On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin,
it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !