SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46e68ffbf9fa628e15b7289b479f94ab2b311ce46190ab83fcf54a8dfe84d339' 
  AND token = 'ykbE1HaePwPvkGZD/tXJZlPVDNy18TGkcYXm18jJmcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}