SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e7b59bc2f3ef5df98db954a4296849b4596dc6bfd14b41f10417af4738a6dfb' 
  AND token = 'sjWGxw/JAFo4OrVlJXmCg2iaHkdYMbTNwfLIAbhWm48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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