The key is hot, and Kuhl does not want to burn himself. By taking a spare shirt and wrapping it around his hand, he thinks he can protect himself from burns. He tries this, and then tries to grab the key. If he can do so he looks at his companions, and says, "It seems unlikely no obold was ever curious enough to investigate this. I am suspicious of this lock, but we are here to investigate."
He takes a deep breath, and inserts the key and his fist into the maw of the carved creature on the door, in order to access the lock. He is tense -- images of childhood stories whereby magic locks come to life and show that they are hungry dance through his head. He's always liked his hand.