SELECT 
  cscart_images.*, 
  cscart_images_links.*, 
  cscart_common_descriptions.description AS alt, 
  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 = 'ja' 
WHERE 
  cscart_images_links.object_type = 'ap_category' 
  AND cscart_images_links.type = 'M' 
  AND cscart_images_links.object_id = '7' 
ORDER BY 
  cscart_images_links.position, 
  cscart_images_links.pair_id

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "ordering_operation": {
      "using_filesort": true,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_images_links",
            "access_type": "ref",
            "possible_keys": [
              "object_id"
            ],
            "key": "object_id",
            "used_key_parts": [
              "object_id",
              "object_type",
              "type"
            ],
            "key_length": "81",
            "ref": [
              "const",
              "const",
              "const"
            ],
            "rows": 1,
            "filtered": 100,
            "index_condition": "((`_testcscart`.`cscart_images_links`.`object_type` = 'ap_category') and (`_testcscart`.`cscart_images_links`.`type` = 'M'))",
            "attached_condition": "((`_testcscart`.`cscart_images_links`.`object_id` <=> '7') and (`_testcscart`.`cscart_images_links`.`object_type` <=> 'ap_category') and (`_testcscart`.`cscart_images_links`.`type` <=> 'M'))"
          }
        },
        {
          "table": {
            "table_name": "cscart_images",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "image_id"
            ],
            "key_length": "4",
            "ref": [
              "_testcscart.cscart_images_links.detailed_id"
            ],
            "rows": 1,
            "filtered": 100,
            "attached_condition": "<if>(is_not_null_compl(cscart_images), (`_testcscart`.`cscart_images_links`.`detailed_id` = `_testcscart`.`cscart_images`.`image_id`), true)"
          }
        },
        {
          "table": {
            "table_name": "cscart_common_descriptions",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "object_id",
              "lang_code",
              "object_holder"
            ],
            "key_length": "107",
            "ref": [
              "_testcscart.cscart_images.image_id",
              "const",
              "const"
            ],
            "rows": 1,
            "filtered": 100,
            "attached_condition": "<if>(is_not_null_compl(cscart_common_descriptions), ((`_testcscart`.`cscart_common_descriptions`.`object_id` = `_testcscart`.`cscart_images`.`image_id`) and (`_testcscart`.`cscart_common_descriptions`.`object_holder` = 'images') and (`_testcscart`.`cscart_common_descriptions`.`lang_code` = 'ja')), true)"
          }
        }
      ]
    }
  }
}