SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0691247e1e368b149a59b6060f6af01274d30e37427fae6453d3a9999943f17' 
  AND token = 'lMKT4a/vR/9VnGeAdloG/nWvUAdBT+Gu5mesfYC+6yg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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