SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4e2e3f6c70d609befed42354512db1c574da4912f6d1d5b62ef5c326246138f' 
  AND token = 'pmMIDcSK8JMGS6YXIV7HD1Z0XmLuQkq7aiBBTVOjswA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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