SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a291a8c9c71e627741d85ed7f0fb7820d6eaee656edeeba20bb9446946def538' 
  AND token = 'F3ZmS+beQ474C9bfKV0PsS2YlsDzK5e+PXnNi6uJpnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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