SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2263d698c001ffaa07f9db0802f13fccdd4ed4692c73bad61653f37ecd694bbf' 
  AND token = '6vTqiwwo6JPq5KZ7eCmIDU3KqI9DwLQL4jc7TuLTHHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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