SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b76cb921bd28eee711c4c199ccd27488935e42e686a0ae79dd03e7679faa34ad' 
  AND token = 'QHlMreYy87vRIITXEswTLkRVu2ANX8zS7x3WDo5L/u8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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