SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a76baaefa05d0864e7a0fd3adb8b0fee3d63938854152d1eb0dfbf1823b1c34' 
  AND token = 'Tu+XUBICqQ696P/FJxJkpvuWn3BPtKstvXzICJhlmB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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