Get all post IDs which have meta key `location` and meta value `Pune`.

get-post-ids-by-meta-value.php

<?php
/**
 * Get Post By Meta
 *
 * Get all post IDs which have meta key `location` and meta value `Pune`
 * 
 * @todo Change the `prefix_` and with your own unique prefix.
 * 
 * @since 1.0.0
 */
if( ! function_exists( 'prefix_get_post_by_meta' ) ) :
	function prefix_get_post_by_meta() {
		global $wpdb;

		// Get all IDs 
		$post_ids = $wpdb->get_results(
			'SELECT `post_id` FROM `' . $wpdb->postmeta . '`
				WHERE `meta_key` = \'location\'
					AND `meta_value` = \'Pune\'
			;'
		);

		return $post_ids;
   }
   // add_action( 'admin_head', 'prefix_get_post_by_meta' );
endif;