SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340f4c9a26ac3e454aa642ebc4873e7fdf8ed9aa5f39562446691afa1d5fe537' 
  AND token = 'Dr/+Dd57qAHBmsSsNnwCxfBHTQl2i2QFx6UJjSqsRJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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