SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68e6fd98bdc414d429e7b1ffae0909b4a929391eef868adcadc3a5eef0a000b5' 
  AND token = 'siFcOLxrpyRFM0QddqqbC8Oa0ib915qshK5RrniB6PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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