SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b6c61c504d5480f8007217cadc1894ee33fd364428cdb3d840c41e6b25f2cd' 
  AND token = 'h28SR2yZbgxv9ONtpJk8cFtD5uprgrWr6DCpUK89WlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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