Prepare the spices by mixing the salt, black pepper, onion and garlic powders, paprika, 1 tablespoon thyme and lemon zest together with a fork. Add the olive oil and mix in. Place the chicken on a sheet pan, trim any excess fat with scissors and discard. Rub the spice paste all over the chicken skin (and under the skin when easy to do so), getting into all the nooks and crannies. If you have a little extra spice mix, sprinkle it in the main cavity of the chicken.
Set up the air fryer by taking out any extra racks or trays, leaving only the base tray for the chicken to sit on, then spray the air fryer basket with cooking spray (or brush with high heat cooking oil). Place the chicken breast side down in the air fryer, spray the lemon halves or drizzle with olive oil and arrange in the cavity. Cook at 350º F for 30 minutes. Flip the chicken so it’s breast and legs side up and cook for 10 minutes longer. Check to make sure the thickest part of the breast meat has an internal temperature of 165 º F then take the chicken out and let it rest for 15 minutes on a cutting board before carving.
Remove the lemon halves, carve the meat, arrange on a platter. Sprinkle the remaining 2 teaspoons of thyme leaves over it. Squeeze the lemon halves all over, covering the meat with juice. Drizzle more olive oil over and sprinkle with flake salt.