SELECT 
  name as review_username, 
  comment as review_comment, 
  last_review_timestamp 
FROM 
  cscart_product_last_review 
WHERE 
  product_id = 20687

Query time 0.04361

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_reviews",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "idx_product_id"],
          "key": "idx_product_id",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["const"],
          "rows": 5,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "<subquery3>",
          "access_type": "eq_ref",
          "possible_keys": ["distinct_key"],
          "key": "distinct_key",
          "key_length": "3",
          "used_key_parts": ["list_review_id"],
          "ref": ["dev_db.cscart_product_reviews.product_review_id"],
          "rows": 1,
          "filtered": 100,
          "materialized": {
            "unique": 1,
            "query_block": {
              "select_id": 3,
              "temporary_table": {
                "nested_loop": [
                  {
                    "table": {
                      "table_name": "p",
                      "access_type": "ALL",
                      "rows": 25675,
                      "filtered": 100,
                      "attached_condition": "p.`status` = 'A'"
                    }
                  }
                ]
              }
            }
          }
        }
      }
    ]
  }
}