SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f497e765d523d0482d99e811de9947d51bfb9949f429d1a6cf8c86207ff3e779' 
  AND token = '/ttvwfV6Y358ONjzmsLWbV+8fh/2tA3moweWAUrHhVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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