SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97dcc3532a73042f9564a2bf02c564d11100a3b7cad0708d68e587fa64e5f890' 
  AND token = '7pTw1TSrJACS86bFwXp0i3tnuqjoojSSBtbjeAQeysY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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