SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7589f5603abc0365a37171ddf3efe4ebb76138daeacf8989da542f0ce368764' 
  AND token = 'S0Yy0ECWI05/+Cnmfsev7ZIGFnIEtyKDugTDDnvbe2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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