Question

if site name does not have REQUEST URI then index.php should come
else if URL is example.com/key the file pages.php?tkey=key should come.

When I set this way images in subfolders are not loading

RewriteRule ^/?$ index.php [L]
RewriteRule ^(.*)$ pages.php?page_keytkey=$1 [L]

Please advice

Answer 1

Try preventing the recursive loop that Peter Szymkowski pointed out.
Also consider not redirecting existing files as Michael Berkowski said.

RewriteRule ^/?$ index.php [L]
RewriteCond %{REQUEST_URI} !^/pages.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ pages.php?page_keytkey=$1 [L]

You can read more at http://wiki.apache.org/httpd/RewriteCond for example.