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 (
    70575, 70574, 70576, 73491, 74226, 74227, 
    74936, 74935, 74934, 74937, 74964, 
    74963, 74962, 74961, 74965, 76891, 
    76889, 76890, 79224, 79225, 79223, 
    79643, 80590, 80591, 80592, 80722, 
    80723, 80724, 80869, 80870, 80871, 
    82802, 82809, 82811, 82812, 82804, 
    82805, 82806, 82807, 82793, 82794, 
    82795, 82796, 82797, 82798, 82808, 
    82799, 82800, 82801, 83085, 83076, 
    83077, 83078, 83079, 83080, 83081, 
    83082, 83083, 83084, 84207, 84208, 
    84405, 84406, 84407, 84408
  )

Query time 0.00488

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": 65,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70575,70574,70576,73491,74226,74227,74936,74935,74934,74937,74964,74963,74962,74961,74965,76891,76889,76890,79224,79225,79223,79643,80590,80591,80592,80722,80723,80724,80869,80870,80871,82802,82809,82811,82812,82804,82805,82806,82807,82793,82794,82795,82796,82797,82798,82808,82799,82800,82801,83085,83076,83077,83078,83079,83080,83081,83082,83083,83084,84207,84208,84405,84406,84407,84408)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}