SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f6f47bd615d33164e73b71b3958f2ab55f0faee94aa23aecab3f869adf7598f' 
  AND token = 'PUJFrT+pJxv/E5mz7Va8+jDhTRW++ZjTgxkG596aXbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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