[SQL] Select records from table until a duplicate

Is there a way I can select a set of records from a table ordering by a column till a duplicate.

TableName --> temp

Columns --> key1, key2, key3, key4, rowCount

Select condition

1. Order by rowcount
2. Till a duplicate on combination of key1, key2 and key3

key1 key2 key3 key4 rowCount
k1.1 k2.1 k3.1 k4.1 1
k1.2 k2.2 k3.2 k4.2 2
k1.3 k2.3 k3.3 k4.3 3
k1.1 k2.1 k3.1 k4.4 4
k1.5 k2.5 k3.5 k4.5 5
k1.6 k2.6 k3.6 k4.6 6

The select query should return me the following records

key1 key2 key3 key4 rowCount
k1.1 k2.1 k3.1 k4.1 1
k1.2 k2.2 k3.2 k4.2 2
k1.3 k2.3 k3.3 k4.3 3

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