SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d3fe15bda9887c262b94dd52d5a96dd3887ff08340313743ad7fe77da4c8432' 
  AND token = 'NOFr/o5w20s80wRt11VNaqvBd63dknw3AdLRkDCVfwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}