Curbside pickup. If they're able to take payment over the phone, it's easy enough to arrange. If they are unwilling to oblige, just hold off. If what you need to purchase is an absolute necessity, I would suggest finding an alternative to the product if you're not comfortable going there in person.
You can also report the business if you'd like, but this has the potential to cause more harm than good (owners can be slammed with a hefty fine or ordered to close temporarily). Personally, I would call the store, ask to speak with a manager/owner, and voice your opinion about your safety concerns. Then, ask if they offer curbside pickup. If they do, pickup your order, then sanitize the bag exterior and everything the bag may have come into contact with (hands, car seat, table, etc.).