SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '349ec8a58bb9b5aad379b60de52141537c58b71d85b1fb9b84f566becbec9388' 
  AND token = 'wXwjCqwoeKnWdS2r2vknlbM896NhmqfjVvUzLKZIB7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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