SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbb250a84765349925bff577d1dfea3d7adbd92c19705f3692ce2c3814c4faf4' 
  AND token = 'nAgdWJZECvuU0SwUZg8r3PfzhZ6e1NGZuHoRrJN6Tjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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