SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '295e073c2726dbbb19ce19418e60a5963ed854877349b098455110f3b1b7bb77' 
  AND token = 'nx+DKeZ9SXUxQ35EIZn4p+J++DVqMVzLCi83EThs2Fw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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