SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84ec3d8ece8d74f0abf26617a5d5e1fd0460fc53738f235710b3017d65319fd7' 
  AND token = 'oMJeztH1vHbStnw4N5AboVZBT2yd6K0u+ACAEcSsDZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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