SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3afe9feebdfde673e14d09c4b1656cda37e772f64b0d47f717b10f819bb70f2d' 
  AND token = 'k3MjDwbIIWeCb3lgDE3UnO/A+SQurCryOP/DOynOvuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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