SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '196603708d65e6a8735f6afe5dcc55daddb1b4291d008c32afe52a0cfeb2da4a' 
  AND token = 'TnqNtiy+aRWCZYwQTOLJzjck6+22lYM1JjkJ5Hm/AtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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