SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92293af800169e16262d54abe349234635b0a7f34d9b7c26284f7742646c0f8' 
  AND token = 'YXrVYuIdWmhpiRtt/H3PHxecqo5OB5j/Pthr5WKcfwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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