SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc918f939f0cb79260888783f786b4ea06db4ffa37b9da4cf0b847fd153d8642' 
  AND token = 'b7T/MnlIdGJp4w8WrVXwe5etYBevWAnPH8F4Xi5xDe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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