SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '209b709ae1b6e8d7320c3a67918d2a57b6696827da9160259909b443284b0c56' 
  AND token = '4hGI2ScltAFpl0wEF8zWSnS/7ddOjT5xQe/0kWYgyCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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