SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1793cb46e759c54f1a0501ba36891d049b55c2290a028476f0a0d2c585aac64e' 
  AND token = 'bCmJdoF/wxPwscqeyg2PS37wkVZxd2LydyGxm2EkKz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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