That melanin skin is so hard to pull off correctly in color choices, and you absolutely nailed this character.
I like the loose-hanging thin chain / necklace that's more over the pecs. The two chains around the throat seem a little tight. That may be intentional, a part of the whole kink / sensual theme of the whole piece, but like even the lighting on the loose chains are better than they are on the chunkier ones on the throat. They stand out, and they seem like either a last minute addition, or an improvisation that diverts away from any reference photo that was used.
Like you have all of this realistic three-dimensional look in the cloth around him, his musculature, the hands coming from offscreen, and then the lock is looking squarely at the viewer, as if a two-dimensional asset that represents a lock more than it IS a lock.
All of this could be intentional, but it's an observation that can be made. Color choices are fantastic, from the cloth to the hair to the painted nails and pills popping out of this dream-like background. I tend to phone in my BG's a lot, so I admire the creativity in how you did what you did to fill in the negative space.