SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b81afe43c1c8a633f3fbe82f126711047cd7983e63961c7c939ad996655fdee0' 
  AND token = 'Uh8Xo8jkMg6OW8v8wRxLvgvKt9s4zVlpBMUZfKHMJ58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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