SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81fe34948dee5e3bbcb52351cbdb9bc3d0a983b213d316da171d8d854512208a' 
  AND token = 'JSih8TMCMeD33byYeL7nV/l5J4sm/H8ZiFxjxg4K30A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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