In Revelation 9:1–2, an angel is given a key to, or control over, the bottomless pit, and he uses the key to open that pit. Later, an angel is seen locking things in the bottomless pit (20:1–3).

Revelation 20

New International Version

The Thousand Years

20 And I saw an angel coming down out of heaven, having the key to the Abyss and holding in his hand a great chain. 2 He seized the dragon, that ancient serpent, who is the devil, or Satan, and bound him for a thousand years. 3 He threw him into the Abyss, and locked and sealed it over him, to keep him from deceiving the nations anymore until the thousand years were ended. After that, he must be set free for a short time