SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44b9769e5dcbae455d638851646b85b64af9457339245e3befd174e1b50a66e3' 
  AND token = 'W/8329voTGdaIByfRmG+VqScAVwfm7s6PJMzjuWdMKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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