Spray air fryer basket with oil and preheat the air fryer to 400°F.
Pat each salmon fillet dry on both sides.
In a small bowl, whisk olive oil, garlic powder, mustard, paprika, salt, and pepper together until smooth. Brush each salmon flllet generously with the mustard mixture.
Place two fillets in the air fryer and air-fry for 6-8 minutes, depending on the thickness of the salmon and desired degree of doneness. You will want to do this in two batches so you do not overcrowd the basket, so when the salmon is cooked, remove to a plate to rest.
Spray the basket again and repeat with the remaining two salmon fillets.