Get access by product SKU for Woocommerce

functions.php

<?php 
//place code in the end of functions.php in theme
add_action('template_redirect', 'wc_sku_redirect');
function wc_sku_redirect() {
	$parseUrl = explode('/', $wp->request);
	if(isset($parseUrl[0]) && $parseUrl[0] === 'product') {
		$pid = wc_get_product_id_by_sku($parseUrl[1]);
		if($pid) {
			wp_safe_redirect(get_permalink($pid));
			exit;
		}
	}
}