SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '668f6539a4750e12ae14c9ce922edaa16c67e298e3cedcb890b5d197a1fe72d4' 
  AND token = 'A9jQEIFnRnXbYdMpjjypsjElvImc0dY8RzEBWszFWnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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