"Real key lime or something else?"
Looks like the Key Lime pies I used to make. I found the yellow color a little off-putting so I started putting a drop of green f/c in.
And for the Florida purists: the little yellow limes in So Cal are called Mexican limes out here. Same species, I suspect, but since they're not grown in the Keys, I guess they should be called "Mexican Lime Pies." But nobody does.