SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5009bfe57f357054a9b17cde3148af672d764a5740d900c8341a17c4b418203' 
  AND token = 'FcO4wjP27DVooPwxgly7Sahw1LwPH4pdneUjn9hMBvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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