SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '209f6bff55ca2d6afa61c0a71ba75d862935d9bc737764e58140b32ddaf72942' 
  AND token = 'gijdo5tXkllr+DoTFewuor4N8UyuMFPGB5zMZkPMdd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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