Create new Records with Unique Randomized Token using a Single Query

insert_record_with_valid_unique_token.sql

# Insert into table with a unique token column without a loop
# using `LEFT(UUID(), 8)` as the unique string generator for simplicity,
# feel free to use whatever method you'd like, including generating those
# in memory and putting raw strings into your query

INSERT INTO table(column1, column2, token_column)
SELECT "column1_value", "column2_value", token FROM (
  # create a derived table containing five (feel free to increase)
  # potential unique strings
  SELECT LEFT(UUID(), 8) as token
  UNION SELECT LEFT(UUID(), 8)
  UNION SELECT LEFT(UUID(), 8)
  UNION SELECT LEFT(UUID(), 8)
  UNION SELECT LEFT(UUID(), 8)
) as tokens
WHERE NOT EXISTS (
  SELECT 1
  FROM table
  WHERE token_column = tokens.token
)
LIMIT 1;

you may need to convert the unique string, i.e.,

# SELECT LEFT(UUID(), 8)
SELECT CONVERT(LEFT(UUID(), 8) using latin1)

(assumes the token column is defined as latin1)