SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42346a80faf5a059e250f6f9dd9bdbec882e6d2ad3ff934fbd4ce63400108260' 
  AND token = 'vMuyRHWxWqgZZC6pkP3bzNl21pLsKJqDDmywFv7D9pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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