SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1447138c2e438a8e7e71cebb127f736dca546ea5924c4ee5d59b7be7672f4579' 
  AND token = 'hkTvmcPN2zN1pfyVeXePRvtSrz/xgeaMDkvFiLhWu2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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