SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcfc673d251fc85aa15fc8cd32370b0770e8e861d30e57370c2a4ba7bdc1ccf6' 
  AND token = 'eJi43MHdx9QROZOxZ9kRYBQdFNWX/rxvdo3lj16sYJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}