How to make apache rewrite for / only?

Question

Apache HTTP Server

Hello everyone, friends.
Tell me, please, is it possible to do only such a rewrite on apache, which would translate only a link like: test.com to www.test.com , and for all other links with a direct call, such as test.com/abrakadabra , did not rewrite.
I tried to do this:
RewriteEngine On
RewriteCond %{HTTP_HOST} test.com$ [NC]
RewriteCond %{REQUEST_URI} ^/$
RewriteRule ^(.*)$ www.test.com [R=301,L]
But it redirects to all links, not just an empty URI.
Thank you!