Key of the Abyss

Revelation 9:1 The fifth angel sounded his trumpet, and I saw a star that had fallen from the sky to the earth. The star was given the key to the shaft of the Abyss.

Revelation 20:1 [The Thousand Years] And I saw an angel coming down out of heaven, having the key to the Abyss and holding in his hand a great chain.

There might be two keys the "Key to the Abyss" and The "Key to the shaft of the Abyss".