SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ef3b38f7146943dff7ee725f262ea831ad63d9640193951da6b9fa629d1d6bb' 
  AND token = 'UfZVc9ACIhUCy4wR7GB3D6BYAxcM8NVvNZBJyHzYTzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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