SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ef2fc6f047f1b9905a220325a4b479e90b36003c99d9091e588e5c63292ca4' 
  AND token = 'wO4tqwmpTkFhfvEjSJZHpx2wpASHUe7EpqAvGpdykTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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