How to correctly change the rewritecound condition for the cache?

Question

htaccess

Hi all!
here I made such a rule, if there is a file in the cache folder, then we show it, if not, then we skip the rule, but the rule does not work because of the first condition

RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_URI} ^/$
RewriteCond %{DOCUMENT_ROOT}/cache/index\.html -f
RewriteRule ^(.*)$ cache/index\.html [L]

Please help me find the problem, thanks!