SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f55633ddd687a46d9b54a375d805929178cbeaadd38a008c93c73f5719a2cbd' 
  AND token = 'otJY1xw6wjk39bvemg5Ry5VFzI2+eDEHzWoHu0/sxFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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