If brining the chicken, add the chicken and 1 tablespoon of the salt to a large bowl. Fill with cool water, cover, and refrigerate for at least 1 hour or up to overnight.
In a small bowl, combine the remaining ¾ teaspoon salt, pepper, garlic powder, onion powder, paprika, and brown sugar (if using).
Transfer the chicken to a cutting board and pat dry. Brush the chicken with the olive oil and season all over with the spice rub.
Preheat the air fryer to 375°F. Arrange the chicken in the air fryer basket and cook for 8 minutes.
Using tongs, flip the chicken and cook for 6 to 8 minutes more, or until the internal temperature of the chicken reaches 165°F on an instant-read thermometer.
Let the chicken rest. As it rests, the internal temperature should rise to 165°F, which is the perfect done temp for chicken breasts.
