SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c19b2ddfd51cac84350e31a3c992bef48973bae428c392820ee315071949813' 
  AND token = 'oiacM9z597xcW0SFJxfV15s6kDncbr7X5ZKscClj0LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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