SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5334d94168767e8b835958f568386753392afe87466319c0a879f4e91c5d774c' 
  AND token = '2NoUOzH7riIJDYaRmmMGXA7r6RhGVhMjq+gh4RlGuWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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