SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be56bd9a67ee3384ab8dba7cd00d3bbd4a4be83b860a0dedfbb79d2f77897feb' 
  AND token = 'dNbMrk5Niezu53gp+lyW7wVjJ+Y+sRB9QMbF8yG6bzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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