SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50b2efc3a4304eab888a90f39e47aa7fb342f457f45f3bbecca953e7f9d4ae09' 
  AND token = 'kT6UMpVjBpN4bLWr5lDEvj6Ut7AeiSXmXfiDeahIMvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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