SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23a8a1284c39eb7ec1493e2052542bb5f9e7ae8310cb467139a37508b5927221' 
  AND token = 'NwpdUG7AhcFgAJ58fQiyPlND4Z1SjnsqgDzZfmVyXHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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