SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f561be341b91e5eab0a1520bbf4f23180a92731e53b8461eea6fe639d3790a' 
  AND token = 'nI+qLPVtRwEEivsn3ZdGSAw02urLKfqh9gfJP4iGTXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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