SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbfb04f8c643bd93ba3032811e381abf9e6d57fced65750426fb0ee9199bf768' 
  AND token = 'hiMfHZ+6bJnRhfDRALCu/LwDQXutw+rXJj1GSqY7Khc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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