SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b572dfc5e8f46bcc10ece03eec7669149bfc709624c5422499abc0267ecd61' 
  AND token = 'm0yqUyEMhENh4t/Nc4nwvxZ0TtvPGNJNxbmheeGyr/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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