SELECT 
  cscart_images_links.*, 
  cscart_images.image_path, 
  cscart_common_descriptions.description AS alt, 
  cscart_images.image_x, 
  cscart_images.image_y, 
  cscart_images.image_id as images_image_id 
FROM 
  cscart_images_links 
  LEFT JOIN cscart_images ON cscart_images_links.detailed_id = cscart_images.image_id 
  LEFT JOIN cscart_common_descriptions ON cscart_common_descriptions.object_id = cscart_images.image_id 
  AND cscart_common_descriptions.object_holder = 'images' 
  AND cscart_common_descriptions.lang_code = 'en' 
WHERE 
  cscart_images_links.object_type = 'product' 
  AND cscart_images_links.type = 'A' 
  AND cscart_images_links.object_id = 29986 
ORDER BY 
  cscart_images_links.position, 
  cscart_images_links.pair_id

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_images_links.position, cscart_images_links.pair_id",
        "table": {
          "table_name": "cscart_images_links",
          "access_type": "ref",
          "possible_keys": ["object_id"],
          "key": "object_id",
          "key_length": "81",
          "used_key_parts": ["object_id", "object_type", "type"],
          "ref": ["const", "const", "const"],
          "rows": 7,
          "filtered": 100,
          "index_condition": "cscart_images_links.object_type = 'product' and cscart_images_links.`type` = 'A'",
          "attached_condition": "cscart_images_links.object_id <=> 29986 and cscart_images_links.object_type <=> 'product' and cscart_images_links.`type` <=> 'A'"
        }
      }
    },
    "table": {
      "table_name": "cscart_images",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["image_id"],
      "ref": ["cscart_migrate.cscart_images_links.detailed_id"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_images_links.detailed_id = cscart_images.image_id)"
    },
    "table": {
      "table_name": "cscart_common_descriptions",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "107",
      "used_key_parts": ["object_id", "lang_code", "object_holder"],
      "ref": ["cscart_migrate.cscart_images.image_id", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_common_descriptions.object_id = cscart_images.image_id and cscart_common_descriptions.object_holder = 'images' and cscart_common_descriptions.lang_code = 'en' and trigcond(cscart_images.image_id is not null))"
    }
  }
}

Result