SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71557cba320661a6fca550133718ba40561467787b8c22ab2430945320cf104c' 
  AND token = 'si5rpn9I64TfSh1clueYFZ6VTstNKm/+jLMwSjTMqQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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