如何防止MySQL Union使用全表扫描？

Question

我使用Union编写此查询以从3个不同的表中获取结果。 Explain表示它执行2次全表扫描。如何优化此查询以使其不执行全表扫描？这是Explain See Explain image here的直观表示。 Explain Results part 1 Explain Results part 2

                  (SELECT f.name, f.description, f.location, f.copyright, f.location, f.orientation, f.cws_asset_key, pst.title, f.related_media_key, f.media_type, f.is_visible_at_press, f.created_at, 'content' AS 'type' 
              FROM ContentRelatedMedia f 
              INNER JOIN Content c ON f.content_id = c.id 
              INNER JOIN ParentSeries ps ON c.parent_series_id = ps.id 
              INNER JOIN ParentSeriesTitle pst ON pst.parent_series_id = ps.id 
              WHERE ps.is_visible_at_press = true
              AND f.is_visible_at_press = true
              AND ps.company_id = :company 
              AND f.is_archived = false 
              AND f.media_type = 'image' 
              AND (f.name LIKE '%' :name '%'
              OR f.description LIKE '%' :description '%'
              OR pst.title LIKE '%' :title '%')
              )
              UNION 
              (SELECT ff.name, ff.description, ff.location, ff.copyright, ff.location, ff.orientation, ff.cws_asset_key, pst.title, ff.related_media_key, ff.media_type, ff.is_visible_at_press, ff.created_at, 'season' AS 'type' 
              FROM SeasonRelatedMedia ff
              INNER JOIN Season s ON ff.season_id = s.id
              INNER JOIN ParentSeries ps ON s.parent_series_id = ps.id
              INNER JOIN ParentSeriesTitle pst ON pst.parent_series_id = ps.id
              WHERE ps.is_visible_at_press = true
              AND ff.is_visible_at_press = true
              AND ps.company_id = :company
              AND ff.is_archived = false 
              AND ff.media_type = 'image' 
              AND (ff.name LIKE '%' :name '%'
              OR ff.description LIKE '%' :description '%'
              OR pst.title LIKE '%' :title '%')
              )
              UNION 
              (SELECT fff.name, fff.description, fff.location, fff.copyright, fff.location, fff.orientation, fff.cws_asset_key, pst.title, fff.related_media_key, fff.media_type, fff.is_visible_at_press[![enter image description here][1]][1], fff.created_at, 'parent_series' AS 'type' 
              FROM ParentSeriesRelatedMedia fff
              INNER JOIN ParentSeries ps ON fff.parent_series_id = ps.id
              INNER JOIN ParentSeriesTitle pst ON pst.parent_series_id = ps.id
              WHERE ps.is_visible_at_press = true
              AND fff.is_visible_at_press = true
              AND ps.company_id = :company 
              AND fff.is_archived = false 
              AND fff.media_type = 'image' 
              AND (fff.name LIKE '%' :name '%'
              OR fff.description LIKE '%' :description '%'
              OR pst.title LIKE '%' :title '%')
              )

由于