SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '672e018859fee54bd60d151f3a02e6551e61da635781fdfce8bc630cc749c7f4' 
  AND token = '+fwg44IAtkGR6geKTs2iFUD6ZcaIxfZ9pmOSG+FwBdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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