SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac65be85d777b6ae3320ae13dea473a92fc10f303a859326ba901447eeedbd12' 
  AND token = 'khGudzidyP7CgIDCqqRVSBTjFG79rjsf08eIk7AY1sQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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