SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcc51ba2cab4d8540811c7fd07b714667daf14d84e6e27a11fcdc8a6efadab61' 
  AND token = 'XdzuTRZQBntm+1HN6UKQdIZ/I58xs24pPUCBN6eDJSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}