SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e0a313aab034aaf431b45e82da8c8cde80772604909c6191df52849758a219f' 
  AND token = '7L/JQLkln4j5qzSNzpQniocFiZDkkf9eTEM2LMI7Z0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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