Fast fix. Get something flat like a thick piece of plastic to cover the drains when not in use. Can put something heavier, like a bottle of water, on top to help hold it down.
Better fix. Change the floor drains to ones that have a flap on the bottom that close when no water is draining. Keeps odors and critters out. There are 2 types. Those that use a spring to keep it closed and those that have a weight flap. I like the spring ones better, they seal tighter. Just saw a third type on Lazada that uses magnets. No experience with those.
Global house sells some or on Lazada.