SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c4564e5fec91ee97d6a8af359ea292fc44d550fab67d64ec34d6d769988483' 
  AND token = 'VRS5VbiSgRdhHK22ocds9e0P0BXQ93RM9kRqIK4NAeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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