SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '395fd89b44ce3cbb8c76f7dc05d2afe11aece081efea034ff0841d624850b2be' 
  AND token = 'ZrgIoxGkeSI4YtDCFlwwt6ulLWlPnbRiYwADrRh+vvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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