SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686b7ad9a4215c0f5b33626e0d8ad93a91646c3b34c9fff7d938e2af8599ff87' 
  AND token = '/YLi40d1L4vBP4f069x3wrL6gAc0Ql5JGjL3gz+bxZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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