SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81098276996189d9cc50137f049f515c12017daaae4a7429def3551486a8b21e' 
  AND token = 'WMUo/MGFQ8MEDxUt8GJPBAwpPoqfv4hmbp9cfa+VboU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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