SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3adb42e38847d464f09ec72ed45a5f0e331d4b639251994c9521191a7cbe5726' 
  AND token = 'Sq8WzXfRxH4DgnK1Nt/S9X78iY9LlPVg4zFpPoWKYTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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