SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'vi' 
WHERE 
  pfv.variant_id IN (
    75701, 75697, 75698, 75699, 75700, 75705, 
    75702, 75703, 75704, 75712, 75706, 
    75707, 75708, 75709, 75710, 75711, 
    75715, 75713, 75714, 75719, 75721, 
    75720, 75724, 75725
  )

Query time 0.00816

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 24,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (75701,75697,75698,75699,75700,75705,75702,75703,75704,75712,75706,75707,75708,75709,75710,75711,75715,75713,75714,75719,75721,75720,75724,75725)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'vi'"
        }
      }
    ]
  }
}