SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139d1cc4076710abbe5172439c13781d5725bf5d0b7114761d43836cb52549ae' 
  AND token = 'VG0oLGxA5mdFLIFcURIgIbeSNVLGt3O1EI80tZLeCyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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