Set your air fryer to 400ºF and lightly coat the basket with non-stick spray.
Combine garlic powder, paprika, dried thyme, salt, and brown sugar in a bowl and stir well.
Dry the chicken thighs using paper towels, then sprinkle the seasoning mix evenly over each piece.
Arrange the chicken thighs skin-side down in the air fryer basket, drizzle olive oil on top; you may need to cook in batches.
Cook for 8 minutes, then flip the chicken and air fry for another 8 minutes.
Check that the chicken reaches an internal temperature between 160ºF and 165ºF and the skin is crispy; if needed, cook for an extra 1-2 minutes for more crispiness.
Allow the chicken to rest for about 3-5 minutes before serving.