SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '74e22a89ca9ab401031ea130c53df207660c0f92c8b72a80e74b20a591a52941' 
  AND token = 'Bost16qYHqur1ir86yDBA7ZyRrpH1XlwTQ2pduBURcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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