SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e420ec5662fb916b9e0d4638cb23c2601ba28bac0c508bb335de0d083fa37c4' 
  AND token = '08QTufEoP2Caq36wIUjuUYA1vBnlRVDz/IexHBLKPnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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