SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '723f8dce40440aefffe2fbc650fd5a56a59650e5b9377317463cf8675818f689' 
  AND token = '976gAVod2kNNt9gp6VIAyidL4zVy2mioRVS0zEdm4Ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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