optimized db query for post_ids or posts count

ffdb.php

<?php
function ffdb($args){

    global $wpdb;

    $post_type = $args['post_type'] ?? 'post';
    $post_status = $args['post_status'] ?? 'publish';
    $term_id = $args['term_id'] ?? null;
    $meta_key = $args['meta_key'] ?? null;
    $meta_value = $args['meta_value'] ?? null;

    $select = $args['select'];
    $select_query = 'ID';

    if( $select == 'count' ) {
        $select_query = 'count(ID) as count';
    }

    $join = '';
    if( $term_id !== null ) {
        $join .= " LEFT JOIN {$wpdb->prefix}term_relationships ON object_id = ID";
    }

    if( $meta_key !== null ) {
        $join .= " LEFT JOIN {$wpdb->prefix}postmeta ON post_id = ID";
    }

    $query = "SELECT {$select_query} FROM {$wpdb->prefix}posts {$join} WHERE post_status = '{$post_status}' AND post_type = '{$post_type}'";

    if( $term_id !== null ) {
        $query .= " AND term_taxonomy_id = {$term_id}";
    }

    if( $meta_key !== null ) {
        $query .= " AND meta_key = '{$meta_key}'";
    }

    if( $meta_value !== null ) {
        $query .= " AND meta_value = '{$meta_value}'";
    }

    $result = $wpdb->get_results($query);

    if( $select == 'count' ) {
        return $result[0]->count;
    }

    $ids = [];
    foreach( $result as $row ) {
        $ids[] = $row->ID;
    }

    return $ids;
}