SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b580e9c50ad957f271074f21452c0b72be81c1ee35a69e275851e9bc165643' 
  AND token = 'WD96ufoUUsevZ53u9oRsvkrb4EwVqsv85tul13ZhtFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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