SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b311530596fc5bb4f55b795e40ef43293df07e502610b595eca413de7466806' 
  AND token = '5fS3clMlXHefHk63GXrnASPHxldka2A8lk3fYnaAjjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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