SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d73b817f0c7b92e4e8ca88cfccdd2dfed34bbf8773007964f34d559c540f548' 
  AND token = 'QqtuSjrRANDvFIAdTUalEkt3AdsQj32amwQtgHIvhUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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