SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f21274ca2c51561ccb5758b9bf0e2ff32ca349d45a5bd6aa616209c85378caa1' 
  AND token = 'OcFO9wBwzHwUFsD5Bz8ISNiVJ5uboCl+Y6TS8uvRjXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00076

JSON explain

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