SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d391c17d0f80fe4322b07dae60957c995c1bf44637ebc2301ec3bb5542ade3' 
  AND token = 'WSX5Np6ZfHEqJevt2X8hGkE+sVIlVGs1slkC/T6X518=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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