SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3f99bb9b878eba8b1a77454aa03594c66095bdb585b3b0a4597a1de743730709' 
  AND token = 'W3GceVwMD+ICEk+ln66MpbuZEwHxEZjT2M7vUg1UaPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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