How to customize SQL query

Question

I have 1 module with model, resource model and collection. Now I can get data with SQL query: SELECT main_table.* FROM table_abc AS main_table; I want to customize this query by adding WHERE clause (for example: WHERE 3 = 3). How can I do that? I tried to add $this->getSelect()->where('3 = ?', 3); into _initSelect method of collection but It didn't work (When I see SQL log I realize SQL not change)

Here is my full code (Collection class):

<?php
namespace ScPortal\SubscriptionItems\Model\ResourceModel\SubscriptionItems;
use Zend\Log\Writer\Stream;
use Zend\Log\Logger;
/**

Class Collection

@package ScPortal\SubscriptionItems\Model\ResourceModel\SubscriptionItems

/
class Collection extends \Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection
{
    /*
     * @var string
     */
    protected $_idFieldName = 'subscription_items_id';
/**
 * Define resource model
 *
 * @return void
 */
protected function _construct()
{
    $this-&gt;_init(
        \ScPortal\SubscriptionItems\Model\SubscriptionItems::class,
        \ScPortal\SubscriptionItems\Model\ResourceModel\SubscriptionItems::class
    );
}

protected function _initSelect()
{
    parent::_initSelect();
    $this-&gt;getSelect()-&gt;where('3 = ?', 3);
}

}