SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a637c3bd17bc79897383d738421aa93a61d5b6b33ddbf4a64b99ac1947963c23' 
  AND token = 'PYF+p2nyqDDhx6EtoZrZePLW6dLvyEcFPzn7qdBSTpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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