SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '301994cfcc221c864e8df1bc52807868febd77e9f63ed8eca6af3cecf9ecdf6a' 
  AND token = '3Wuay7Flcwgv3RJZuVEJ5txMfNagFyWJIYbtatmEUgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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