CREATE TABLE table_35270 ("Outcome" TEXT, "Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Partner" TEXT, "Opponents in the final" TEXT, "Score" TEXT)

What date was the score of 6 3 6 4?
SELECT "Date" FROM table_35270 WHERE "Score" = '6–3 6–4'
SELECT "Date" FROM "table_35270" WHERE "Score" = '6–3 6–4'