SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '708479e21ae1e3eee5d60c7800bfca99c2ca18e34932e393910919c808cd6d02' 
  AND token = 'RFQEMJN8v8yQP24vFUxGzZaAKcZ3tFTPF/VIXmiQpjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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