SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5597191ad82051dde24c2113faf6ce8d17b46f04299360f59691c707fbf39a89' 
  AND token = '2mAURe2QR0YK2tq2/DgbbIZLypgZLFPDziN+xbP7i34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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