SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39bbd96c4ade173eb2ea677cb3d97ed53e5df55ccb6880af6652001b5e19d211' 
  AND token = 'X41MJziw91mtERtlfADfuQllrIQz+PnuLDf6g/mtZK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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