SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '88c756a89f5b79db17fc336e7b5e96eb786af0d6ca0d614558f3538eaf8ad38c' 
  AND token = 'WF1tvkSKrBi1L8d++4ha/t33MnqIMt1gi4uXIQflIR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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