SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef5803422963c1499186195f330f455757966db5d2e3695e149a1da82d793ced' 
  AND token = '+Km665y7DKE8WrvXfGmcOmHrEQVTi9KIWfQWuj6XLuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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