SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261698d28b41d0fa31b182f4cbac0f403eaa3f36e48d21211982ef77b22146ed' 
  AND token = 'kEIJrpZf43RPrS1aXp3Tx3Ky45hMrW+cqtkvRWsnGQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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