SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0234cb9ca6025e529499dcb77a53186a21007f86305af19e84b9c7435112bb99' 
  AND token = '+kYN3NuRSG+oi+tLK5x+/ODRzi6kcfWlhRVx+VzwNvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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