SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '459d846df824f3bcf7a700e616eff3597ba990509850dee68ef82a6efeae0aaa' 
  AND token = 'Qf2heV40tZhUie3cL02fMo+HzmHDbkSTxJih2LPeicQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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