SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258a517dac494b12bffa6b7cf6a9d3f85ac96d6c8e350616842a0e950b125d9d' 
  AND token = 'GYiBdS+WD+SA/4WtK0zqy71DmfJqD+CoFbclOLwJhL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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