SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3af031048e338d027ae541be5748957b660cac096c37af0554c409758db048c2' 
  AND token = 'oUvU6DHu4V60y0oUWVOv7UZkcNsAUXR3oonjBzuyM0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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