SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44f5bfdb02d1fd89391048d0115aa6604383e7d930d815f341d969b39581f25b' 
  AND token = '9PeHgwoOUjTbPixkC1A+Xwdlt5gVehX1NjqhDvzxC98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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