SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '318d06ed4968c7a5006869249c6ebd31852a639450df336e0efb96e378110622' 
  AND token = 'YMpfTH8zBgnUTzQT1GNQv1nTlCyfU78bkn9VFPaPvls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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