<div class="center">
                    <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
                    <?php include 'product.php' ?>
                    <?php endwhile ?>
                    <nav class="pagination">
                        <?php
    $big = 999999999; // need an unlikely integer
echo paginate_links( array(
    'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
    'format' => '?paged=%#%',
    'current' => max( 1, get_query_var('paged') ),
    'total' => $wp_query->max_num_pages,
    'prev_text'          => __(' « '),
    'next_text'          => __(' » '),
) );
    ?>
                    </nav>
                    <?php else : ?>
                    <p>
                        <?php esc_html_e( 'Sorry, no posts matched your criteria.' ); ?>
                    </p>
                    <?php endif; ?>
                </div>

function search_filter($query) {
  if ( !is_admin() && $query->is_main_query() ) {
    if ($query->is_search) {
      $query->set('post_type', array( 'drzewa_formowane', 'pre_bonsai' ) );
    }
  }
}

add_action('pre_get_posts','search_filter');