SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a257e03c376579d2972a54a8382a548e002dfc82c29d9cb96784b41411115ccf' 
  AND token = 'zGSRQHRABbhz5wSMU1EUwb+/0RabYBkMKQXJQZZtVYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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