SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3802428a8da41f59e1948444bf0a71c58af32e4deb8778e1c4fbcee53e00e84' 
  AND token = 'UeOSgju+pBtScf89wl50jK5xNmzybaguMZfsj+mBIsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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