SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0687664a7ca7c9d7d5fdc2f0def76c89a9c8bb18187273af7784d41349e3e33c' 
  AND token = 'OtAMO1NmeGqkfsz6FvXmSbKh8HulEkU2+iqK//VX6zY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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