Possibilities are to store your luggage at the airport and visit Male city. There is a ferry going every 10 minutes from the airport to Male’city which costs 1 USD p/p one way
Other possibility is to visit the nearby airport hotel, Hulhule Island hotel and make use of their facilities. The hotel offers different packages like a swimming pool package of 72 USD p/p which includes transfer, luggage storage, 1 drink, use of towels, Wi-fi, 10 minutes of reflexology, sun beds, swimming pool, showers and changing rooms. No reservations are needed for this and cost can be paid directly to the hotel reception.
Or possible day room use in a guest house in Hulhumale depending on availability.