SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5dd9de59a4d9a7c3b34f7d2e9f819362f21a35a6b951334d338e2ee75227d5c' 
  AND token = 'J4hhuBEBFPHFQDAt/j5BUo+CwYOBlDY0WOPAwEOzVKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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