SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835b5e12ab31570aad52af2aca0292dd7b743d3f97832b3c4ccb0bbf7ce7ac33' 
  AND token = '8fnjs53RJJrRnlx+q40LysBrJPPYGhbsniGFnosQSvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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