SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cbcbd4439b8e00658fc7e26473dbe24b059655727c9de103d246591fe7e770c' 
  AND token = 'KQ4Cy3mh8W8/v21bmbBX2Ufgk1VK+BGQiETH/zB2HhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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