自定义ModRewrite以重定向到控制器方法

I am currently using Alipay which POSTs responses to my OpenCart website URL [on success] that is this http://192.168.16.58:8080/index.php?route=api/order/callback.

However, one condition for Alipay is that it stops reading the URL after the ? separator, so instead of POSTing data to my route, it instead POSTs to http://192.168.16.58:8080/index.php

Because of this, I am interested in using RewriteEngine to write a custom rule where when I set the notify_url as http://192.168.16.58:8080/index.php/api/order/callback, it actually redirects to http://192.168.16.58:8080/index.php?route=api/order/callback

What I have is the following:

RewriteRule ^index.php/api/order/callback.$ index.php?route=api/order/callback [L]

My logic is that if Alipay is going to index.php/api/order/callback, I would instead be redirected to index.php?route=api/order/callback, however, using both GET and POST, I am instead redirect to my OpenCart homepage.

RewriteRule ^api/order/callback$ index.php?route=api/order/callback [L]

This would enable:

http://192.168.16.58:8080/api/order/callback

to:

http://192.168.16.58:8080/index.php?route=api/order/callback