This is simply:

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{QUERY_STRING} (^|&)7eyS= [NC,OR]
    RewriteCond %{QUERY_STRING} (^|&)8dkG= [NC,OR]
    RewriteCond %{QUERY_STRING} (^|&)viYF= [NC,OR]
    RewriteCond %{QUERY_STRING} (^|&)Wv3y= [NC]
    RewriteRule ^ - [F]
</IfModule>

Or am I missing something?