SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a29a76dd6f847b487a78318259ee3fdf997d22a4b26a670c7398fa581d51c069' 
  AND token = 'WNEeRujM4D9YUhhQWsDo/cDmcism4J9KJ6K/rJCeXlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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