SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd38e413ca994aa3e1eaaecf1aa271b2cdd4408350b1a189ae5506d2fee17241' 
  AND token = 'pNbMSsFNk/aqA314jsx7HKCBDYngo4093u5RZioUBeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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