SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd4322879c628667ba17a7a7d7d5ee6d348f0b340ec5381469070b38465b3a69' 
  AND token = 'JUdzvQtn7uK5hVpAxHZjtY94tOdA3LYd/HN8Ih6awhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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