Show the size of every index on a table

SELECT index_name,
       ROUND(stat_value * @@innodb_page_size / 1048576, 1) AS size_mb
  FROM mysql.innodb_index_stats
 WHERE database_name = 'shop'
   AND table_name    = 'orders'
   AND stat_name     = 'size'
 ORDER BY size_mb DESC;