SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea916f2b745ff71f64d5570a70b55c974bf2ff44058b61d8d6902354e843a8d2' 
  AND token = '8nUKhE1jkdojcIMvOtvJI3XhmC8iuDueMA/o19+sZAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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