SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f834930061b638c99753a7b178c132d5a06e811dc5aefc389b204d391c3a3ce3' 
  AND token = 'HhHCzfm22TB6x0vJzozm38ukPgqObmXn59Dng7XkIM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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