Uniti Atom: possible to prevent indexing of USB drive?

Is it possible to instruct the Unity Atom - e.g. through a particular directory of file naming convention or other means - not to index files on a drive attached to the USB port?

I just put a 1TB M2 SSD drive in a tiny USB enclosure and copied all my music to it. Overall, more than 40,000 files. Since the Atom can index only 20,000 files, and since I have everything organized in a tidy folder structure anyway, I would like to prevent the Atom from indexing the files on the drive (I imagine it might also slow down the unit in day-to-day operation). Is there a way to do that?