SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139f77dcf71cf5d37313b128587fdf56aa8f68295f7902ab0bbd1090c45dae78' 
  AND token = '4O/bSmCJBIEB3FWgb0ZUcLgps9bleNKmAIL7xqQdBhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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