SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2d3e2598143b1ac1b286981ddd87ba78e64565f61e0d8cba6a8d42a69c67a20' 
  AND token = 'IUuZqwWiZoXB/YMbYNwdU59IJz6HiRrv0wWWLeyauMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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