morimasato

Automatically update the search index of QuickSearch. 
You’ll need an <a href="http://www.quick-solution.com/quicksearch" rel="nofollow ugc">QuickSearch Content Key, API key</a> to use it.

WP Plugin QuickSearch

Automatically update the search index of QuickSearch.

mattsgarage

The search functionality in woocommerce doesn’t search by sku by default.
This simple plugin adds this functionality search facility of your site, in both the public site and admin panel
Just install and activate – no config required.
Tested with Woocommerce 1.5.6, 2.0.7, 2.0.18, 2.2.4, 2.2.10, 3.4.4, 4.0.1 and 4.2.0
See the <a href="http://www.mattyl.co.uk/2012/12/11/woocommerce-plugin-to-search-products-by-sku/" title="accompanying blog post" rel="nofollow ugc">Accompanying blog post</a> for more information.

Search by SKU for Woocommerce

Extend the search functionality of woocommerce to include searching of sku

WP Plugin QuickSearch vs Search by SKU for Woocommerce