Passing second parameter to controller having 404

I have a view file that is listing all the sections as a list

<li>
     <a href="{{route('asset.view',array('theme_id'=>$asset->theme_id,'key'=>"$asset->key"))}}">{{$asset->key}}</a>
 </li>

in my route file, I created a route to the view function like this

Route::get('asset/{theme_id}/{key}', ['as' => 'asset.view', 'uses' => 'AssetController@view']);

laravel's default URI format is asset/view/{theme_id}/{key} and my problem is the second parameter key having an extra /. so the final URI become asset/view/1254125/section/page and it returns a 404 page.

how can I fix this?