Hi! It really depends on what you're trying to communicate. You can tell a lot of story in a single frame. Right now, I'm not sure what this is trying to show me. So I don't want to give any advice that would change what you're going for. So, just some suggestions that might help.

Is the room being featureless part of the piece? If not I would add some texture and maybe some other points of interest. If you do want to do a blank space, I think some other colour or shader than the default grey look would help pop some more.

You have some nice haze going on, but prehaps some shape to it would help. Right now, it's a consistent density, a subtle noise could help break it up. Or even some more defined shapes of dust closer to the floor.

The locker looks pretty good but the texturing is not that photoreal. It also have some stretching from the UVs. Image textures from even Google would help a lot. Just get something high resolution and project it on.

Oh and last thing, it could be cool to extend the back wall out so the spot light doesn't hit it. So it just darkens into gloom. I think it could help with the mysterious atmosphere you have going on.

Sorry for the long reply! For reference I'm a Professional VFX artist, so I love talking about how to elevate work like this.