SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7e14f4bba124b4f105d975e9919568d15252119bc0ff0924dc65c858b95e350' 
  AND token = 'e6/NUpsi+nhsuAujaVTp6O4t8lxYTL564WmBYyMt2sM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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