SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c377cdb80a653c7db2fc6ae204a98da83d947a882f5ace0fd75625903774f02' 
  AND token = 'CSSE8VMQsAgQnAz+HrR3Gqt0W5PqKnzeIVaz0u9jf3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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