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 (
    68596, 68595, 68594, 68593, 68592, 68597, 
    87019, 87020, 69631, 69630, 69629, 
    69632, 70759, 72794, 72795, 73957, 
    73956, 73955, 73954, 73958, 73972, 
    73971, 73970, 73969, 73973, 74609, 
    74608, 74607, 74610, 87216, 80108, 
    80109, 87215, 87214, 82441, 87711, 
    87712, 87713
  )

Query time 0.00447

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": 38,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68596,68595,68594,68593,68592,68597,87019,87020,69631,69630,69629,69632,70759,72794,72795,73957,73956,73955,73954,73958,73972,73971,73970,73969,73973,74609,74608,74607,74610,87216,80108,80109,87215,87214,82441,87711,87712,87713)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}