CREATE TABLE t (
    id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
    sum_component FLOAT
);
INSERT INTO t (sum_component) VALUES (0.5), (0.6), (0.4), (0.5);

SELECT t.id,
    @cumulative_sum
    FROM t
    CROSS JOIN (SELECT @cumulative_sum:=0) a
    WHERE (@cumulative_sum:=@cumulative_sum+t.sum_component) > 1.3
    ORDER BY id ASC LIMIT 1;

SELECT t.id,
    @cumulative_sum
    FROM t
    CROSS JOIN (SELECT @cumulative_sum:=0) a
    WHERE (@cumulative_sum:=(@another_variable:=@cumulative_sum)+t.sum_component) > 1.3
    ORDER BY id ASC LIMIT 1;

MariaDB [a51]> SELECT t.id, @cumulative_sum FROM t CROSS JOIN (SELECT @cumulative_sum:=0) a WHERE (@cumulative_sum:=(@another_variable:=@cumulative_sum)+t.sum_component) > 1.3 ORDER BY id ASC LIMIT 1;
+----+--------------------+
| id | @cumulative_sum    |
+----+--------------------+
|  3 | 1.5000000298023224 |
+----+--------------------+
1 row in set (0.00 sec)

MariaDB [a51]> SELECT @another_variable;
+-------------------+
| @another_variable |
+-------------------+
| 1.100000023841858 |
+-------------------+
1 row in set (0.01 sec)

mysql> SELECT t.id, @cumulative_sum FROM t CROSS JOIN (SELECT @cumulative_sum:=0) a WHERE (@cumulative_sum:=(@another_variable:=@cumulative_sum)+t.sum_component) > 1.3 ORDER BY id ASC LIMIT 1;
Empty set (0.18 sec)

mysql> SELECT @another_variable;
+-------------------+
| @another_variable |
+-------------------+
|                 0 |
+-------------------+
1 row in set (0.01 sec)

mysql> SELECT t.id, (@cumulative_sum:=(@another_variable:=@cumulative_sum)+t.sum_component) AS cumulative_sum, sum_component FROM t CROSS JOIN (SELECT @cumulative_sum:=0) a ORDER BY id ASC;
+----+----------------+---------------+
| id | cumulative_sum | sum_component |
+----+----------------+---------------+
|  1 |            0.5 |           0.5 |
|  2 |            0.6 |           0.6 |
|  3 |            0.4 |           0.4 |
|  4 |            0.5 |           0.5 |
+---+----------------+----------------+
4 rows in set (0.04 sec)

mysql> ALTER TABLE t MODIFY sum_component DECIMAL(4,2);
Query OK, 4 rows affected, 2 warnings (0.16 sec)
Records: 4  Duplicates: 0  Warnings: 2

mysql> SELECT t.id, (@cumulative_sum:=(@another_variable:=@cumulative_sum)+t.sum_component) AS cumulative_sum, sum_component FROM t CROSS JOIN (SELECT @cumulative_sum:=0) a ORDER BY id ASC;
+----+----------------+---------------+
| id | cumulative_sum | sum_component |
+----+----------------+---------------+
|  1 |           0.50 |          0.50 |
|  2 |           1.60 |          0.60 |
|  3 |           2.40 |          0.40 |
|  4 |           2.50 |          0.50 |
+----+----------------+---------------+
4 rows in set (0.18 sec)