That's a pretty low profile fireplace so I'd think you could just mount it into the brick right above the black housing.

If you're looking for something more adjustable though, this is an option: https://www.amazon.com/MantelMount-MM340-Above-Fireplace-Mount/dp/B01MS1MHET

MantelMount MM340 Above Fireplace... https://www.amazon.com/dp/B01MS1MHET?ref=ppx_pop_mob_ap_share

This one.