SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9883d6a752939bc4dd2cf60164f596429808f5e54301ac59e0948ecd27db587' 
  AND token = 'KaqaWiH+bcjmxUBvRoj8F9pr4eTXB/iigIDuWLCYO2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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