SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1050a84919274fd499bad1351d1a83ff88ae598c2f1804c22cb795da443fde37' 
  AND token = 'RkGsOoRo5vsRyATYlZQGrFrZYo+kWhGm138jiro1tvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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