SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b197ac1dd02994b9a16bac2de1c36dee73cfbbd041cb889601e61b14587172c' 
  AND token = 'nT7Uk5FYl6F82m4Qyj+3rl6q67aQuWQ7b6zIWqIxsJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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