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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df9dfdf752d04b96768cc8730bb733ec24455fc1fb78b7bc1fe12e91fd63a9e9' 
  AND token = '7GR7csb8gcSYavCrIJZpxR5gcW2zXr1aV9yqAS+EFhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}