SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5a00205644ad9c80d09f9260320aa35b43769cfff68045b834a1d814f12b47' 
  AND token = '14UE+fmzjpp4M1ielJSn7qC4/l8NPpSfD6Da9iLrn3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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