SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56d2d378af0f7f3518410ebf84bccf5080fb70f81c0f4496fb75dca803bd49bc' 
  AND token = 'wclAKlGvUm0wmc+Cosvxu/n32WeSkHah2OkWh0coKxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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