SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f573ac199785e0d1afde8eade9f8ba684a1a4736ee326d7afe7213b676cdc334' 
  AND token = 'n0xUXoZlZqmdnAgB8TNHk8MdD/ZmEzTqGrE5eIcis0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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