SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8739ea5c18aa64c6a925164d8cbc43181c757a921a7d4a2cdd7ab20358328f93' 
  AND token = '/Pkmdsd1Cjp7pPTt8+vBkXkRfSdXJFokVZRG8q8FNHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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