SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3136c9bc99ad637e3c4a646ffe731167dda31611cc0e3c974e68fec01c77dbbe' 
  AND token = 'NjhQkA88PqGJ6ey5AAmj65YNMZQY98gZ8F10P+zWng0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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