SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f27bd7969c5c6d15743fb57de528aff6ba1264b80bf075ccbf7a3718e5729978' 
  AND token = 'GD31U++FuvIfRPhJgnF9hbcfL5hHmywDqnpihull+nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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