SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2a1d0af494fd0e2219ee9991b729a6bca3661d2b40575edab47a9287ed073f5' 
  AND token = 'MtrRFe49Jd+eo68Ha7POkZfcHzHkTxRqJlgxagynsLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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