SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ec001b8ff96bd05758e580d2d4267746403fac6bf3b6f238f181323d8df3b5fb' 
  AND token = 'Ul9JWmyvJNaf7tmN+e1zSJzQBI6swiVV/7wFh0dUUhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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