SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c4e6f178d3f4b4522ef21cb0555787b17e3c3f813d5a4b0d29af14199fd8d7' 
  AND token = '6lsHV7Yl3zyYyZpIwf+kCB9B/CRNonKQ86WF4/KW250=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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