SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59d629302567031c36fac468ea6aa7aeebed1aa1aad81574a01ae4d1e82c4f36' 
  AND token = 'iZyBohrI+XGjNWuywSmG9GPak9IZhMC7DLzbPuGsQyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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