SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '184668a63b03443294dd74589d79067a6abcae5cce2f878c9f33a9029b125314' 
  AND token = 'iGbb9UWGjv3xpoFVh9ieLGp5Gmd1KYTg/UhDgD/wULQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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