SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39348742274688a5743dc6cdabde7ad4f22c243bf761126888fa398418321872' 
  AND token = 'q83b7uIIsHuFM3bJLYZyl2ZDZeg6Uv1nRxT1QgIvgXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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