SELECT 
  a.artist_id, 
  a.name, 
  pa.is_remixer 
FROM 
  cscart_label_manager_artists AS a 
  LEFT JOIN cscart_label_manager_product_artists AS pa ON pa.artist_id = a.artist_id 
WHERE 
  pa.product_id = 124626

Query time 0.00027

Result

artist_id name is_remixer
18797 Datcher N
18820 Tigerhead Y