SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ad750df1e8d527b640e0217da72d80cb5d119cf73915f07ece3f1b994ee094a' 
  AND token = '6ePiPExgCLhRYcgMi2GoWWK0hobM6Vm0ho8hlnvtknE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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