Ignore files in non-existent paths using .htaccess - apache

Question

I am having a problem with rewriting.
Here is my .htaccess-file
RewriteEngine On
RewriteBase /
#ignore non-existent utility-files
RewriteCond %{REQUEST_FILENAME} \.(gif|jpe?g|s?html|css|js|cgi|png|ico|txt)$
RewriteCond %{REQUEST_FILENAME} !-f [OR]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* - [L]
#load existent utility files and don't rewrite them to index.php
RewriteCond %{REQUEST_FILENAME} \.(gif|jpe?g|s?html|css|js|cgi|png|ico|txt)$
RewriteRule ^(.*) $1 [L]
#load other files if they exist
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule ^(.*) $1 [L]
#load index.php
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php [L]
The last part is working but I want to avoid that my index.php is loaded when the code requests a non-exisiting image (as: www.mysite.test/images/foobar.png)
The first RewriteCond-Line should check if the request matches a file of image, JavaScript, and the like and the second RewriteCond line should check if the file does NOT exist.
The third one should check if the folder exists.
If the match succeeds NOTHING should be loaded.
It works but only if the folder exists. If the folder if the image doesn't exist it doesn't work.

Answer 1

You have many redundant rules. You can simplify the to:
RewriteEngine On
RewriteBase /
#ignore non-existent utility-files
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} \.(gif|jpe?g|s?html|css|js|cgi|png|ico|txt)$ [NC]
RewriteRule ^ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]

Answer 2

Ok there was still an issue with existing files, as Member anubhava said.
My final solution is:
<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>
RewriteEngine On
RewriteBase /
#load files if they exist
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule ^(.*) $1 [L]
#ignore non-existent utility-files
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule \.(gif|jpe?g|s?html|css|js|cgi|png|ico|txt|php)$ - [L]
#load index.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php [L]
This solution includes php-files in the second rewrite-rule. Because I have some php-files that are actually css-files and loaded by the browser.