SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc41289216ea68dd81c2361b8e708b4a2cbabf297bde7c4d22984343f27c1e7f' 
  AND token = 'iBdfzn5y1BW1IslePDg5EdxLpvjNcKMjKA/AMMdugTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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