SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ff59ca569abedb81db632fcaf9e288e04033c65408a6862e25b44a64b05a274' 
  AND token = 'bZ1QZBq4fhMKGtOeFryo7Qqo7EwkKv/ngMP1tTPlWvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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