SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b2f852b96b7dacd39137d571869d3e6e1c61d3148a56cdb6c2571243698bbb4' 
  AND token = 'Um0ca13jyHGAzJ8NfXj6hZenyZGizkUWPuvKVXww2XM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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