SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b68a2a41a8223ec1813bb5f955b1a2f8a2330d103ff36a3e4df8ddb03790320' 
  AND token = '0NZEdgYCMlLunvpaVgSBw0C+UjQ+K7K63SRLIzZv/n0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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