Place thyme sprigs and lemon halves in chicken cavity.
Truss the chicken legs closed with kitchen twine.
Sprinkle the breasts and legs evenly with ⅜ teaspoon salt and ¼ teaspoon pepper.
Place the chicken, breast-side up, in the air-fryer basket.
Set the air fryer to 350°F (no need to preheat); cook for 30 minutes.
Carefully turn the chicken over; cook for 15 minutes.
Carefully turn the chicken over again; cook until a thermometer inserted in the thickest portion of a thigh registers 165 degrees F, 10 to 15 minutes.
Transfer the chicken to a cutting board; let rest for 10 minutes.
Carve the chicken; discard the thyme and reserve the lemon halves.
Sprinkle the chicken evenly with the remaining ⅜ teaspoon salt and ¼ teaspoon pepper; squeeze the juice from the reserved lemon halves over the chicken.
