SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c33573e39099f52aa09a8fa7755d1132ab42302f99f6863e5868b44ff8e388ff' 
  AND token = '4GKfCGnYIjHTI1ooyeikVMnTYySkrycPBjlPBaqbS8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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