Lana's light footsteps rewarded her - and soon enough a key was in her hand, the guard still asleep.  It was hard to tell what exactly the key went to - it was reasonably well made and had a slightly bronze finish on it, meaning it was likely a decent piece of expense to create.  More than that though, her thieves eyes would be able to tell it was specifically made in order to make any sort of traditional lock picking difficult.