SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72268fe07b1af27fb8490f6e010582d5751d454b77ae4ce42a2d75aab36a4387' 
  AND token = 'uhjvSoJwSdutoeTkkBWh/AgUXSFxo+WldBD4l9vrq8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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