SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e56811930f8991cf012596734311f71f653d7d2242392d6e033496d434316a92' 
  AND token = 'msaPbd18weCGahtYFtvwzuX42drVNfBBZxGVzgYu0uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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