SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad54fddc707a087e3243ec4cfbdb041eb3b3615652cc5beaefc781bae71be877' 
  AND token = 'i7QPb9RNlLFRvYfQ1FxPz0rSnhGRp9rs88bDbvVbXUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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