SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a8c276a1df3f281bdc2b9dc4383a3bc964522655a84bb68ae3ffd435a2b8519' 
  AND token = '/sKFPLDXUUfeTWkc264qS1g5vwqFiUsrEOliyVnbOys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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