SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c400bf575fb3f5963882621ab5ab0fb73d38439713819ea171625ba167432309' 
  AND token = 'pbr8fjjNvRNmYlAJzNTFyOCyv9vtVs11ycL8MwSQsKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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