Speed up woocomerce order admin search

Question

I am using the following function to speed up woocommerce order admin search by searching in particular fields only:

function custom_woocommerce_shop_order_search_fields( $search_fields ) {
    if(!empty($search_field = $_GET['searchfield'])) {
      
      //not unsetting $search_fields because we will be returning it if none of the values match
      
      // No need to pass search fields as order id searched by default
      if($search_field === 'Order ID') {
      return array();
      }
      
      if($search_field === 'Phone') {
      return array('_billing_phone');
      }
      
      if($search_field === 'Email') {
      return array('_billing_email');
      }
      
      if($search_field === 'Tracking Number') {
      return array('_wcst_order_trackno');
      }
    }
    
    //if some random value was passed, return array with number and mail, order id is searched by default 
    
     unset( $search_fields );
    $search_fields[] = '_billing_phone';
    $search_fields[] = '_billing_email';

    return $search_fields;
    
 
}
add_filter( 'woocommerce_shop_order_search_fields', 'custom_woocommerce_shop_order_search_fields' );

I need to narrow it down further to search in orders that were created in past 1 year only and not beyond that to speed it up. How to do this?