I'm performing sql requests on table `interim_19` with 67.500 rows. Table is not indexed, and has 7 columns, non of which are unique/primary keys, because main data `Abonent` and `idBase` are repeating, among all data I have like 7-8 distinct `idBases` and ~10.000 different `Abonents`, and the other data like `date` is not reliable in terms of uniqueness. 

**The problem is in slow inner joins on this table.** 

And if I perform `SELECT * FROM interim_19 WHERE idBase IN (1551 , 42286 )` it'll take 1.33 seconds, and `SELECT * FROM interim_19 WHERE idBase IN (1535 , 5406 )` will take 1.9 seconds, whether 

```
SELECT * FROM (SELECT * FROM interim_19 WHERE idBase IN (1551 , 42286 )) 
temp1 
inner join 
(SELECT * FROM interim_19 WHERE idBase IN (1535 , 5406 )) temp2 
on temp1.Abonent = temp2.Abonent

```

takes forever - 147-157 seconds. I understand that inner join does compare every row to every other row on second table, but this shouldn't take this long. OFC it makes duplicates, but I need all 7+7 rows, so...

P.S I'm already trying to index it, so other advices are also welcome.