SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cf9387799df2c4e7bbad1ce14e315e71efa4b2ee30ff691118589d8d8c03ed6' 
  AND token = 'XHhtYzVvrAC5gNZn5Y0aGJEQksrqG+8pEZ2tPk27KZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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