SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '357e2c8bf5554890c1ad95d869226643f09afdcd96cc5b3b31638eae68f89bd4' 
  AND token = '7zM/b4JjrVBu47AEXwc5bV5Y/w1D3qz4iWKkx+CfrZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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