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 (
    69668, 69669, 70239, 70238, 70237, 70236, 
    70235, 70234, 72988, 72987, 72986, 
    72985, 72984, 72983, 72982, 72981, 
    72980, 72989, 73005, 73004, 73003, 
    73002, 73006, 74588, 74590, 74594, 
    74596, 74650, 74649, 74651, 76637, 
    76635, 76636, 80580, 80581, 80582, 
    80583, 80584, 80585, 80586, 81872, 
    81879, 81880, 81873, 81877, 81878, 
    81874, 81875, 81876, 86300, 87462, 
    87461, 86301, 87464, 87463, 86303, 
    86302, 87098, 87097, 87096, 87094, 
    87095, 87452, 87451
  )

Query time 0.01039

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": 64,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (69668,69669,70239,70238,70237,70236,70235,70234,72988,72987,72986,72985,72984,72983,72982,72981,72980,72989,73005,73004,73003,73002,73006,74588,74590,74594,74596,74650,74649,74651,76637,76635,76636,80580,80581,80582,80583,80584,80585,80586,81872,81879,81880,81873,81877,81878,81874,81875,81876,86300,87462,87461,86301,87464,87463,86303,86302,87098,87097,87096,87094,87095,87452,87451)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}