Matthew 16:19 – “I will give you the keys of the kingdom of heaven”
Luke 11:52 – “you have taken away the key of knowledge; you did not enter in yourselves, and those who were entering you hindered.”
2 Peter 1:10, 11 – Although there is no explicit reference to “key” in this sentence which spans these two verses, it is not hard to infer its relevance given the reference to entering the kingdom. Once cannot enter a protected domain without a key.
Revelation 1:18 – “I have the keys of death and of Hades”
Revelation 3:7 (quoting Isaiah 22:22 below) – “who has the key of David, who opens and no one will shut, and who shuts and no one open”
Isaiah 22:22 (quoted in Revelation 3:7 above) – “I will set the key of the house of David on his shoulder, When he opens no one will shut, When he shuts no one will open”