migrating an old URL to wordpress URL

My problem:

I have a website currently running another CMS that exports content via URLs such as:

https://mysite.com/index.php?view=page1

I’m currently migrating this site to WordPress and I want to redirect all old URLs to the new ones

The above URL will go to:

https://mysite.com/page1

Any mod rewrite hack I’ve tried failed because index.php also exist in wordpress.

I’ve tried something like this, but it’s not working:

RewriteEngine On
Redirect 301 index.php?view=some-demo-query-string https://mysite.com/some-demo-page-on-the-new-site

I guess I need some sort of redirection that will be triggered before the index.php being executed.

The number of the URLs I have to redirect is limited (< 20), I can do it for each by hand if I catch the rule…