SELECT 
  c.product_details_view 
FROM 
  cscart_products_categories as pc 
  LEFT JOIN cscart_categories as c ON pc.category_id = c.category_id 
WHERE 
  pc.product_id = 4 
  AND pc.link_type = 'M'

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pc",
          "access_type": "ref",
          "possible_keys": [
            "link_type",
            "pt"
          ],
          "key": "pt",
          "used_key_parts": [
            "product_id",
            "link_type"
          ],
          "key_length": "6",
          "ref": [
            "const",
            "const"
          ],
          "rows": 1,
          "filtered": 100,
          "index_condition": "(`_testcscart`.`pc`.`link_type` = 'M')"
        }
      },
      {
        "table": {
          "table_name": "c",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "p_category_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "category_id"
          ],
          "key_length": "3",
          "ref": [
            "_testcscart.pc.category_id"
          ],
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}