SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e178bf245586935723a77c24b6dab1e60233587c6a461076c258b466966dc4' 
  AND token = 'BG6GFYubCCJR9vG3EFT5XURoDTOhVUxKZ7dvJtIecdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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