SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d121e64add63d361e84925e9698dd9322ae210e6bb50ce604673a25759da736' 
  AND token = 'JBYJjpk7dZC0aG+cJUmTYlxHpjPis3QjhMUufQDWyrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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