SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29176b0f2b7961e81a7ff4c88f1ddaaca50178a4eb6441c5f31947e201b5162c' 
  AND token = 'fjisZ6vNFqWbwqrutjoSmzDrj8IWqu2tpPH//Yvg0DY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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