SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3c8fa99a2864ccf0ba82903798f919534a55f57ded16d21a8264e1b6cf61123' 
  AND token = 'v9LPIyUPzGkZjP21jUYQFRqTsOiws7ujTaleLZ4Rink=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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