SELECT 
  product_id 
FROM 
  cscart_mb_ali_products 
WHERE 
  product_id IN (
    20877, 20878, 20879, 20880, 20881, 20882, 
    20883, 20884, 20885, 20886, 20887, 
    20888, 20889, 20890, 20891, 20892
  )

Query time 0.00014

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_mb_ali_products",
      "access_type": "range",
      "possible_keys": ["product_id"],
      "key": "product_id",
      "key_length": "4",
      "used_key_parts": ["product_id"],
      "rows": 16,
      "filtered": 100,
      "attached_condition": "cscart_mb_ali_products.product_id in (20877,20878,20879,20880,20881,20882,20883,20884,20885,20886,20887,20888,20889,20890,20891,20892)",
      "using_index": true
    }
  }
}