Faça um
INNER JOIN
nas duas mesas:SELECT COUNT(*)
FROM table_1 t1
INNER JOIN table_2 t2
ON t1.column_1 = t2.column_1
AND t1.column_2 = t2.column_2
INNER JOIN
nas duas mesas:SELECT COUNT(*)
FROM table_1 t1
INNER JOIN table_2 t2
ON t1.column_1 = t2.column_1
AND t1.column_2 = t2.column_2