SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ab22d2a69f4378a0cdc890a5236279e67c26d9518b92b2702fc4b69d41982fb' 
  AND token = 'fmsNwC+RGJVcTCBtyYgxXktrwPkBXzt+rJ2W3RVJzlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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