SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '373c7cb848f3dd3554a4036eda191f9784cd4eba741aa9fc9ed04305ce676921' 
  AND token = '6/VXD7hPve+UOWN0zU/SmG61gj2xwfRk1ZjQrXkQ4Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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