SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a9b79e24f5f0732b573ce73b2967a00b996887113584e0431395566567a44bc' 
  AND token = 'Bbbi8zyG8g6/HQgMGIOhvcWOwtfWuErGh+FmxdNG1qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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