SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fecc7a100b6f4fd5f3951a42b6345a9ec238e7be666d528a073680675d5624e8' 
  AND token = 'qz9QgjspGVZsJfnP+JxOfq3T8DbSxG+d2cWVa/4oUqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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