mysql match string with start of string in table

LIKE can be avoided, by truncating the comparison string to each value's length:

... WHERE LEFT('abffagpokejfkjs', LENGTH(value)) = value

Try this:

SELECT col1, col2 -- etc...
FROM your_table
WHERE 'abffagpokejfkjs' LIKE CONCAT(value, '%')

Note that this will not use an index effectively so it will be slow if you have a lot of records.

Also note that some characters in value (e.g. %) may be interpreted by LIKE as having a special meaning, which may undesirable.