SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ef614209b174903012c607a51fe5a64f88f612456968800cb9610757de0df1d3' 
  AND token = 'EnGDBBVLAnAIAEtZHO/urqB/ISojKhzIZHQhxFIaUQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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