SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '995a186bacc19f94c4e82026e3cec2b41b57b56adb986cb8985fb57f7a469c56' 
  AND token = 's39i/2DlIbwW7QACjjOOsSIp/KGKsMPP+zL5oZQZGMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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