SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e8340a188e6aff4b66dd9d34dc482b5b43daae36ac6861478bf387ae5066a7f' 
  AND token = 'dWPtpM9xqRFqyWrMlBKzG1wuN7Uat1R2qmGpKALcMb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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