SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c34a31437ffa3bcbbab7b3c514522b61429bd774af8e15cd95dee624373f636' 
  AND token = 'mLeByJErNoJPs4MXr3LaUq/MlM/hZEzQTcs4KgvYYqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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