SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'cbf784236b82ca7ca0d5ca5777addb825404c7ee65d7f5b51967cebe16660485' 
  AND token = '75mueP58uqyKwvmROcMmdSIU0ludWLvsSaL7Zhyy7u4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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