SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15a056d028044a64bd85205b2a1e94568afc346b124338c6f95a973a9c1c261' 
  AND token = 'TnOO/6qYCKlGKne+GL5vXB8vUT0yxukjnV0HSvgIZhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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