SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f0f8c96c4c61da576c33fea2610f3daba40dc07ae5b0c84f3232d38359d118' 
  AND token = 'I0qw+q5HXeFaiTZlaByDSZnn9s0Th4ZIGATHFkhw5i0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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