SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa0680618d9227a03424d7ea709a1ed13145718e9251a8f8fc0fdbe3f6467d62' 
  AND token = 'RTSJEseikyFS2OOnE+fpNubDjIgRtkTpVoOQxbVALdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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