SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b127e9f3f727523c06895eb7bd0196ff17113562e387f84c9b64534d2662e1f' 
  AND token = 'N6QZE8TO49lga8zYwFfRowQA+/MHPMd9k7UfjC4aw8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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