Essentially, those mask-less hardware store patrons are trying to kill you. I would tell the owners they need a "masks required" sign on the door. That's like patrons spitting their tobacco juice on the floor, or just pissing anyplace that strikes their fancy.

They will find out why they needed masks soon. Major outbreaks are happening right now in Mid-West and rural towns that are not quarantining well (or at all). Just stay away from them. Maybe you can go to that store at a different time or day of the week.

Or wear one of your N95 masks to go to that store and then shower off afterwards and put your mask someplace safe for 24 hours to let the virus on it die.