RewriteEngine On

RewriteCond %{REQUEST_URI} ^/sorting/$
RewriteCond %{QUERY_STRING} ^brands%5B%5D=restaurants&brand%5B%5D=%25
RewriteRule ^.*$ /restaurants? [R=301,L]

RewriteCond %{REQUEST_URI} ^/sorting/restaurants$
RewriteCond %{QUERY_STRING} ^brands%5B%5D=restaurants&brand%5B%5D=%25
RewriteRule ^.*$ /sorting/restaurants [R=301,L]

RewriteCond %{QUERY_STRING} ^$
RewriteRule ^restaurants.php /restaurants.php?brands%5B%5D=restaurants&brand%5B%5D=%25 [R=301,L]

RewriteCond %{QUERY_STRING} brands%5B%5D=restaurants&brand%5B%5D=%25
RewriteRule ^(.*)$ /restaurants.php? [R=301,L]