'Key' in the Bible

And they tarried till they were ashamed: and, behold, he opened not the doors of the parlour; therefore they took a key, and opened them: and, behold, their lord was fallen down dead on the earth.

They would spend the night in their posts all around God's sanctuary, for they were assigned to guard it and would open it with the key every morning.

And the key of the house of David will I lay upon his shoulder; so he shall open, and none shall shut; and he shall shut, and none shall open.