SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '040304047eed2d269057b84ab27805a11073e9a79a30546cf5d278e8de49f142' 
  AND token = 'eIm6SPiVs4BhnO+SFqujCaylF6JglJocK2M+RUQXnAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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