SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffcc9868c721bc01ed68e532202f61a198ba5bb14d6b872eda5d9a6586a44e45' 
  AND token = 'mkHGOLkeritovnAV6kwMpS1ocS73WbBSvtsszi3WCIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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