SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97b4035967e87b149607fbe374203449626f9623e7dd76d533a8b1b3886cbc77' 
  AND token = 'juPJk53w8bIxlTuKj5qjgHfTHIV+XMgyC8Y6JHun1pI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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