SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'df21e8c85acda444fd9a6679e6a93b0cef0fafae30d3ec45914dafb1ab5c9a02' 
  AND token = 't8NhOAYoE8v0uHqxs2lJFdUMK3tiQG2vc5u7B+zgvHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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