Like this

RewriteCond %{QUERY_STRING} main_page=document_product_info&cPath34&products_id=130
RewriteRule (.*) http://mysite/index.php?main_page=about_us$1? [R=301,L]
In the last line depending on how the resulting url looks, IE appended or not, then you may need to change to

RewriteRule (.*) http://mysite/index.php?main_page=about_us$1 [R=301,L]
or

RewriteRule (.*) http://mysite/index.php?main_page=about_us [R=301,L]
Cheers,
Melanie