SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4492355ca7b0973a6e91aec5020a5852c30f7de7762c481bfd17df1396ce4778' 
  AND token = 'qUbY7GQXL1NUf+wEjC2bBYFB9XDqYRGHFtnw6w1AfDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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