SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9983e89e93886ada4eb56921c63c6232640e8589ffdc22ed3ae56d652a3a468d' 
  AND token = 'nwi5xPVWaGcO+SCTpmqDOLTCFONIud4qTlWZBWOOkL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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