SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c0521d55429413f1ec2c9053470dacc8cab4d23c390314565d406d42ff026a1' 
  AND token = 'AQrs9Lch+AQhaKWLKGj2QMjmaN0wDwglAdEnLHhlMQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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