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 (
    68374, 68373, 68376, 68375, 68378, 68379, 
    68377, 68392, 68391, 68390, 68393, 
    68389, 68431, 69898, 69897, 69896, 
    69911, 69910, 69926, 74066, 74065, 
    74067, 74235, 74234, 74233, 74236, 
    74239, 74238, 74237, 74240, 74263, 
    74262, 74261, 74264, 79355, 79354, 
    79356, 79357, 86179, 86180, 86178, 
    86187, 86186, 86185, 86184, 86183, 
    86182, 86181
  )

Query time 0.00330

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": 48,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68374,68373,68376,68375,68378,68379,68377,68392,68391,68390,68393,68389,68431,69898,69897,69896,69911,69910,69926,74066,74065,74067,74235,74234,74233,74236,74239,74238,74237,74240,74263,74262,74261,74264,79355,79354,79356,79357,86179,86180,86178,86187,86186,86185,86184,86183,86182,86181)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}