SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d152cd14cab6ecba7c5131df1ea2035b2490220d061864b68b475261a1dc076' 
  AND token = 'DNX34+lT5srPelBPMqU0SekPxpWfiVKkr66KGvcbka0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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