SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe973077892030eb43babe5c73dc0cb8b3b931c14cd54f7bd641114272ac1979' 
  AND token = 'MUHmReJQLwcIr1pudc1YgyzSUE+bKSpFZoVShp3dJLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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