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SELECT 
  l.label_id, 
  l.name, 
  pl.writer_split, 
  pl.split_condition 
FROM 
  cscart_label_manager_product_labels pl, 
  cscart_label_manager_labels l 
WHERE 
  l.status = 'A' 
  AND pl.label_id = l.label_id 
  AND pl.product_id = 124545

Query time 0.00023

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	pl	ref	product_id,label_id	product_id	3	const	1
1	SIMPLE	l	eq_ref	PRIMARY,status	PRIMARY	3	toolboxdigitalshop_dev.pl.label_id	1	Using where

Result

label_id	name	writer_split	split_condition
119	Cheeky Tracks	0.55	fixed