Place chicken thighs in a bowl. Season with lemon juice, ketchup, garlic powder, onion powder, coriander, cumin, garam masala, brown sugar, chile powder, paprika, sage, and mint. Mix well. Use clean hands to rub the seasoning on top of and underneath the skin of the chicken thighs.

Cover the bowl with aluminum foil and let marinate in the refrigerator, 4 hours to overnight.

Preheat the oven to 400 degrees F (200 degrees C). Grease a baking dish with cooking spray. Spread chicken over the bottom.

Bake in the preheated oven until tender and juicy, about 45 minutes.