Pat chicken breasts dry with paper towels. For best results, pound to even 3/4-inch thickness.
In a small bowl, mix salt, pepper, garlic powder, onion powder, smoked paprika, and cayenne (if using).
Brush chicken with olive oil, then apply the seasoning mixture evenly to both sides.
Preheat air fryer to 380°F for 3 minutes.
Brush each chicken breast with 2 tablespoons of BBQ sauce, coating both sides.
Place chicken in the air fryer basket with space between pieces for air circulation.
Cook for 10 minutes at 380°F.
Flip chicken breasts and continue cooking for 5 minutes.
Apply second layer of BBQ sauce (about 1 tablespoon per breast) to both sides.
Return to air fryer for 3-5 minutes until internal temperature reaches 165°F and sauce is caramelized.
Remove chicken and let rest for 5 minutes before slicing.