SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12993, 12994, 12987, 12988, 12840, 12841, 
    12843, 12844, 12848, 12849, 12850, 
    12842, 12851, 12852, 12839, 12845, 
    12846, 12847, 12836, 12837
  )

Query time 0.00063

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12993,12994,12987,12988,12840,12841,12843,12844,12848,12849,12850,12842,12851,12852,12839,12845,12846,12847,12836,12837)"
    }
  }
}