SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d83a15daa445fabc55ca61f76b6ee382b1a16714a07a743a887b5f30edc9a48' 
  AND token = 'F3yiUvCgUyhv84GC8BYNUcAiFU3kplzN9CZZ2JkSho8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00230

JSON explain

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