Once upon a time computers had such sort of things attached. please C&C
Actually I have one of those on my server 
and it is for attaching a harddrive case into a harddrive carrier to make it mobile. My keys are a bit more detailed, though yours might not be.
Edit: The number is the middle is actually mtl on mine.
Edit2: great textures btw.
You mean this? (my reference - well, you’re right - they serve for removable ide disk case, but i tried them for pc-lock and it works as well). There is exactly one texture here, put on a plane (col & normals), making the floor. a procedural ‘noise’ is applied to both metal parts and plastic (however not very visible on the latter)
Attachments
However, I noticed that the curves are a bit segmented and that you have modeled worng in some parts.
The end of the mtl tube where it attaches to the plastic should be slightly smaller than the rest.
Your modeled key show 3 layers (plastic, mtl, plastic) on the edge where mine just show one layer of plastic.
And you should model a computer and stick it into that, not just a well used floor.
A paintover.
Attachments
It looks like the metal is too thin, both in the barrel of the key, and in the handle. The projections and grooves cut in the barrel are too small as a result of not having enough thickness to cut deeper and wider.
The black plastic case looks like it’s a shell or a case that the metal part of the key is inserted into, so you can see three layers, plastic-metal-plastic, on the barrel edge of the handle, where the key inserts, but the sides should probably be solid plastic since the casing covers the metal on the sides and at the top.
The wire ring holding the keys seems a bit thin, too.
You might want to smooth the barrel, the facets are still visible, and bump up the texture a bit. Cloud or stucci ought to work for the texture on the metal. To make the metal really shiny, set up a separate lamp with “no diffusion” to get more control over the amount of specularity and turn down the “refl” value to get the dark parts really dark.