SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26fe83bc3b2371a89f17d475f86f350a88f2403e45f2b7a04b9f89e309c5669f' 
  AND token = 'gOt48gAq0/mygZPSh3DLbRCa+xYNNKP6zhQQi2+9J7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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