SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852dba7bf937acacddc53e253e8b8654c7330558b55838a849293292d187aa3f' 
  AND token = 'BTkG+37Nn2NUnCin1iKGEukZ0Eexb4E6ilVdILp4qPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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