SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '50e9a0fc334a3eb12651c16576c83d1e4700669f185b95761482cdb68ca2ab89' 
  AND token = 'ESFFkWl2ntcgSK/n9/vrl/rAVHeAdcakFrNC5Np4+BI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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