SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dcf3a6467af1beb50a9e27bcfaf983593085126f52b5758a85ef742c9179971' 
  AND token = 'TCOAsrVDDSj1qOjjJLpa1p17sVTalYDkZIjo5uNDa1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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