SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86f67ce878022d3c630fd1ab6411ac53d27e33e7e1dd5c53a034dc403f5a3e76' 
  AND token = '1dyHqaIWu+DVyaVOq9hp9MLmXhTwnbWyyXtq375kMsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}