SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8cdda3135acbae94b39f17955d3edefa1a1067cb0617e6de8e6456e94617bd6' 
  AND token = 'sUpdk3loEDvVxPE/dyFt91kxHqj8x7MlHie4EqRdgeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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