SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dff4256fac3b21314a2319e33fe8b8dd7a9c80a546f978ced87c5d5829a457a' 
  AND token = 'n+/01VFwqUhH17Zxc4tlhdTzWicJgsvImjQmW1BcKvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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