SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ddd646bad31476d8439ebbf70f6dc3585e26e7724fcc5f4a3016fa9c7e1e48f' 
  AND token = 'Zm9HuAz1FxHWPIVNp6j2A1gWuRqSXCHm/jhZEsYt4U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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