SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87fa00c786d22ee36629bbca0057c858ff688edeb011d36e4fe866d6576c895a' 
  AND token = 'TnSjrhngFs3dZmourNGl1AU/IYmKuxT5ttOgU5/uXtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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