SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd3bb268dbb868172076891e1359b8c0f97c705749a687875a372074825747a86' 
  AND token = 'jQzBlhD73votKOU3kRKVYKEslA1bOzQK3upoABXmhqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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