In a small bowl combine flour with garlic powder, paprika, oregano, celery salt, dry mustard, and salt and pepper. In another small deep dish beat the egg.
Dip 1 piece of chicken at a time into the flour, then in the egg, and finally in the flour again, coating each side well each time. Allow excess to fall off.
Spray basket with olive oil spray. Place chicken 4 at the time in the basket. Spray tops lightly with olive oil spray.
Air fry at 370 °F for 18 minutes. Turn the chicken thighs halfway through cooking time and spray tops again for best results. remove when internal temp is 165 degrees F and outsides are as brown as you'd like.