SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f52e2b3e816fd447f859c6cb78365bf6ce294e312462c40b212b963f142529a' 
  AND token = 'zHJmd7JZT1i4QnOTqV2dJ+CX1JJrfHywctfY354sZak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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