SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bddc68ebed1afebbe116a3546c34da496a582ee0d2d7299e613c7ca920f9bb8' 
  AND token = 'Cu9Qw8DDiBcgFUmTcZmGc/4y4eJJiCBkdBy5/rmkz4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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