SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccf2cbd05a1322d27e85a074891a7f717a731d9f0690bf4d4e8cdcdf885af5c9' 
  AND token = 'pUSeg9I4nkz9xVKCWdMrJ+AIocl7bDJHfIoen9W8GS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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