SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688f09eef11a58bb89ba817e5ba72be0d0ba34117094cc50fc9837dbdd900c55' 
  AND token = 'bmlVlcFUSY5UoQSqklsEh9SL1VXhPD0Tt2Zf3BAj6F4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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