"Yes, but the Apocalypse speaks of the end of times"
Yes it does, but it also speaks of things John had seen, things that were at the time and things to come. At the time of the vision it was around 95 A.D. and Jesus is saying "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." He is saying at the time of the vision He had the keys of life and death, physical and spiritual, which means He now exercises rule and judgment.
But besides, the Church does not teach that the grant of the keys somehow diminished the sovereignty of Christ and took the keys away from Him; it is entirely appropriate to employ the key metaphore to the sovereign judgememt of Christ at all times, and so also to the Church Age. What is not appropriate is to attach the power of the Keys to the laity outside of the apostolic succession, as such transfer is not described in the Scripture and was never taught by the Church.