SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1703f708cb7168f3e059b4ea56c0e3dcd9dc1b93426e92a84f8f4f75c3bb172' 
  AND token = 'AjBgUPnjgoU6QIs7PiCJv/NSgDCkV3FLIYr1tTdrsHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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