I have a mysql table "items" with 2 integer fields: seid and tiid
The table has about 35000000 records, so it's very large.

seid  tiid  
-----------
1     1  
2     2  
2     3  
2     4  
3     4  
4     1  
4     2

The table has a primary key on both fields, an index on seid and an index on tiid.

Someone types in 1 or more tiid values and now I would like to get the seid with most results.

For example when someone types 1,2,3, I would like to get seid 2 and 4 as result. They both have 2 matches on the tiid values.

My query so far:

SELECT COUNT(*) as c, seid
  FROM items
 WHERE tiid IN (1,2,3) 
GROUP BY seid
HAVING c = (SELECT COUNT(*) as c, seid
              FROM items
             WHERE tiid IN (1,2,3) 
          GROUP BY seid
          ORDER BY c DESC 
             LIMIT 1)

But this query is extremly slow, because of the large table.

Does anyone know how to construct a better query for this purpose?