SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bd0b088978f2878e35ab5bdc48cfbbfc2835bcc3a83099390248de79fa7818f' 
  AND token = 'kaBr1wlad2rN/uK9GPvMQa9uxWYvAo1WB5feTq8hk3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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