Speed up a MySQL BETWEEN query
In your query, the join has no conditions. Shouldnt be something like SELECT xxx FROM table1 JOIN table2 ON table1.column = table2.column and xxx.date between xxx to xxx .

Add:
Here is the explain for the test table

explain select find from table1 t1 join table2 t2 on t1.find between t2.from1 and t2.to1;
+----+-------------+-------+-------+-------------------+---------+---------+------+------+------------------------------------------------+
| id | select_type | table | type  | possible_keys     | key     | key_len | ref  | rows | Extra                                          |
+----+-------------+-------+-------+-------------------+---------+---------+------+------+------------------------------------------------+
|  1 | SIMPLE      | t2    | index | from1,to1,from_to | from_to | 12      | NULL |    2 | Using index                                    |
|  1 | SIMPLE      | t1    | ALL   | idx               | NULL    | NULL    | NULL |    5 | Range checked for each record (index map: 0x1) |