SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9702a7ad665045c13dda0bf70da05adaece569eafa5ed53046e66d40e23557ff' 
  AND token = 'm3/ancDvruTVL1ZBUdB5MP6NdhSvwyN6yIDPihl/yoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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