SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f19747a5a86ece5a3942fd91a6278576407cedba702185c204a0b4f8840404' 
  AND token = 'IzhCYNQCtoeqrnu6nhSI9hnFdbPn6XzYUTmhObOohrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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