The meaning of a locker, especially one that is locked, is to safeguard tools or equipment. This speaks of the importance of our spiritual tools and equipment. It must be protected as well. When we have keys to lockers, we have access to spiritual tools and equipment, and aids. I have never seen a locker symbolize our spirits or souls. The human “heart” symbolizes the soul and the human “stomach” symbolizes the spirit of man.
The Keys of the lockers give us access to spiritual tools, aids, and equipment and we must use them responsibly. It does not give us access to our spirits and souls.
I think this dream is a request that you must be more responsible with these spiritual tools and equipment and aids. The tools and equipment and aids are probably the gifts of the Holy Spirit, the word of God, and so on.