SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e68caeea080502123dbd1c3192f3303f492c57c0502d9bdbdaa282ee547f57f5' 
  AND token = 'ktCcX4ImE1ZMpafIqce0Uigyij5CPhoXSCmafN40rv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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