SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a81ceb47d91c63146f68b67f536c4a84f65c253a2834901d07e69982d646047' 
  AND token = 'aljKPkGskQzHT/NU3zZoSA2IFwAhkJDdW+OriWRvk/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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