SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a420cc3093434c5a3f9d6ecbc987f6267c7815900f7315e96446755692c80ef2' 
  AND token = 'uAw4eBO8l/n+FbQan9jRgPumweL46cHTZA84KzJYR/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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