SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '209d9ec4c670d7df48f317319bac5346fe3fa0e25f8ff402a635699a9ebf2807' 
  AND token = 'OtoQzMTPiStC9kw5HFAHuUiprpDKoCFvT22eD3qYIbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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