SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff7fd97fb5b4aef4444e1d6decdfc7b37be41890f2961e57383460867ddeb593' 
  AND token = 'yYuA0wy9abPheNiKpy/8SgTQaiOsLgCBgrvHbQievZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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