The optimization process and recommendations:

1. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.

Optimal indexes for this query:

ALTER TABLE `wp_postmeta` ADD INDEX `wp_postmeta_idx_meta_key_post_id_meta_value` (`meta_key`,`post_id`,`meta_value`);
ALTER TABLE `wp_posts` ADD INDEX `wp_posts_idx_post_type_post_status` (`post_type`,`post_status`);
ALTER TABLE `wp_term_relationships` ADD INDEX `wp_relationships_idx_object_id` (`object_id`);
ALTER TABLE `wp_term_taxonomy` ADD INDEX `wp_taxonomy_idx_taxonomy_term_id` (`taxonomy`,`term_taxonomy_id`);
ALTER TABLE `wp_terms` ADD INDEX `wp_terms_idx_term_id` (`term_id`);

The optimized query:

SELECT
        p.ID AS 'id',
        p.post_title AS 'title',
        t.name AS 'property_type',
        c.name AS 'listing_type',
        pm.meta_value AS 'address',
        pm2.meta_value AS 'latitude',
        pm3.meta_value AS 'longitude',
        pm4.meta_value AS 'price',
        pm5.meta_value AS 'bedrooms',
        pm6.meta_value AS 'baths',
        pm7.meta_value AS 'show_date',
        p.guid,
        wm2.meta_value AS 'image' 
    FROM
        wp_posts p 
    INNER JOIN
        wp_postmeta AS pm 
            ON pm.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm2 
            ON pm2.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm3 
            ON pm3.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm4 
            ON pm4.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm5 
            ON pm5.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm6 
            ON pm6.post_id = p.ID 
    INNER JOIN
        wp_postmeta AS pm7 
            ON pm7.post_id = p.ID 
    LEFT JOIN
        wp_term_relationships AS r 
            ON (
                p.ID = r.object_id
            ) 
    INNER JOIN
        wp_term_taxonomy AS x 
            ON (
                r.term_taxonomy_id = x.term_taxonomy_id
            ) 
    INNER JOIN
        wp_terms AS t 
            ON (
                r.term_taxonomy_id = t.term_id
            ) 
    LEFT JOIN
        wp_term_relationships AS v 
            ON (
                p.ID = v.object_id
            ) 
    INNER JOIN
        wp_term_taxonomy AS z 
            ON (
                v.term_taxonomy_id = z.term_taxonomy_id
            ) 
    INNER JOIN
        wp_terms AS c 
            ON (
                v.term_taxonomy_id = c.term_id
            ) 
    LEFT JOIN
        wp_postmeta wm1 
            ON (
                wm1.post_id = p.id 
                AND wm1.meta_value IS NOT NULL 
                AND wm1.meta_key = '_thumbnail_id'
            ) 
    LEFT JOIN
        wp_postmeta wm2 
            ON (
                wm1.meta_value = wm2.post_id 
                AND wm2.meta_key = '_wp_attached_file' 
                AND wm2.meta_value IS NOT NULL
            ) 
    WHERE
        pm.meta_key = 'property_address' 
        AND pm2.meta_key = 'property_lat' 
        AND pm3.meta_key = 'property_lng' 
        AND pm4.meta_key = 'property_price' 
        AND pm5.meta_key = 'property_beds' 
        AND pm6.meta_key = 'property_baths' 
        AND pm7.meta_key = 'property_show_date' 
        AND x.taxonomy = 'property-type' 
        AND z.taxonomy = 'listing-type' 
        AND p.post_type = 'property' 
        AND p.post_status = 'publish'