SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    41945, 42013, 42014, 42015, 42016, 42017, 
    42018, 42019, 42020, 42021, 42022, 
    42023
  )

Query time 0.00067

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rows": 12,
          "filtered": 100,
          "index_condition": "cscart_products.product_id in (41945,42013,42014,42015,42016,42017,42018,42019,42020,42021,42022,42023)"
        }
      }
    ]
  }
}