SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'efdd865552fbb97f833c2f2ffbd1687559fd7794d529a30fb895079cfa953d51' 
  AND token = 'oFx2ue0dS8EKEI9mdHZelXlUnXli2WoqcgmLLN3dbyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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