SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '676aa3b7b3700fde188b2a8eedd50e7e3495bf0fa3736d134a145a7067fd34ab' 
  AND token = 'VmjhCoGcsP9IveW7F5mC93IjXTRiNv3hoYTLI6AWijw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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