There is one set of keys, that is the keys to life and death, and Jesus holds them. He received the right when He became "Ressurected". It was not just the willingness to die, it was the power to return to life that shows that He is God in the flesh.
Revelation 1:18
I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
Even Jesus pointed to His ressurection as proof...
John 11:25
Jesus said unto her, I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live:
It was not the cross but the resurrection that was where the power of the testimony of Jesus as the Son of God.
Acts 4:33
And with great power gave the apostles witness of the resurrection of the Lord Jesus: and great grace was upon them all.
It was the resurrection that cause such a flurry among some of the Sadducees who did not want to believe in Jesus's power over death, who prophesied, then fulfilled this divine claim, otherwise they would have to believe that He is the Son of God.
Luke 20:27
Then came to him certain of the Sadducees, which deny that there is any resurrection; and they asked him,
Acts 24:21
Except it be for this one voice, that I cried standing among them, Touching the resurrection of the dead I am called in question by you this day.
Remember it is the resurrection that shows the power of God, He is the only one who can give life. He can breath life into the clay, and it can become a living soul.
Romans 1:4
And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead:
It is our blessed hope also to be resurrected just as Christ was.
Romans 6:5
For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection:
The biggest excitement for the first century was the risen Christ. This was the explosive force of truth, that propelled believers into wanting to live as Christ lived, so that they may also be found worthy to be resurrected into a new life. It was the main thrust of Paul's preaching.
1 Corinthians 15: 11 Therefore whether it were I or they, so we preach, and so ye believed. 12 Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead? 13 But if there be no resurrection of the dead, then is Christ not risen:
Paul pointed to the resurrection many times with deep convictions as to what an astounding event that was.
Philippians 3:10
That I may know him, and the power of his resurrection, and the fellowship of his sufferings, being made conformable unto his death;
So did Peter....
1 Peter 1:3
Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
So let it also be our blessed hope, for we have the firstfruits of resurrection in the body of Jesus Christ who was raised from the dead and has gone on before us.
Revelation 20:6
Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.