SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9e9bf31c0813ef9f6b08ba0ddbed975f739b8e24fb358e5c1a77487c29128ff' 
  AND token = 'tvtRgC2Z9bZDBTlJOUqndaGqa6VSxPkgJshmbz8GWLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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