Preheat the air fryer to 400°F (200°C).
Pat the salmon fillets dry with paper towels.
In a small bowl, mix olive oil, garlic powder, paprika, salt, black pepper, onion powder, and cayenne pepper if using.
Brush the salmon fillets with the olive oil and spice mixture on all sides.
Place the salmon fillets skin-side down in the air fryer basket.
Cook for 8-10 minutes, depending on thickness, until the salmon is crispy outside and flakes easily with a fork.
Squeeze lemon juice over the cooked salmon.
Garnish with fresh parsley and serve with lemon wedges.