SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '527c79d6512ec0346478d70b1f23654d9b9f1a3d3e2e66b348b1250f03cd1fd3' 
  AND token = 'uEgKli7LAVp+8+i+HrJxoQoeObp/BaxdROyP3nJDw+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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