SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7817ac581f21fe229bd73b19c189a940f9f60236c85e0aa7ff016d84cecd1505' 
  AND token = 'R/xT62BjdJTpKrMv+O15wrnxpYZpOrWPhgfcfUJDHE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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