SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1dd2088e05f75366d9547f8bf8142aecde1b3445073e3b063c87648ba15c27c' 
  AND token = '55zPT6lwiCPYxh7CZhwtdKpgh3HtQFa+hBd29lm9lh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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