SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dd70fc20ebc90afc5f2dced0d4eeab0b4938fc51d666456fe527b33a111e851' 
  AND token = 'mjIgmDau1rL+zYSv2bmdQCjAqXUJBNa207jCBbOny7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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