SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d518f2e1d20aac386552038c3c92df067cbfb3e1a90b251e4125e3cf82946c6' 
  AND token = 'Ih0MMjbHm6Pw7mDVigMfSQFBTzRKRawAKW+wq1xp/Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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