SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '148e1f558cda3674a9d48d188973b34fd17d2a7397ad4feb7ab0921f35e0c817' 
  AND token = '28ZWcq+VVBiKuztqzRszKLHLqFr3tIz1jfaVvW4FxBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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