SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b2ab496ca4d608eee327099c1ba8323eb8d009f9daae12cd20577116fd8b04' 
  AND token = 'msozOlqPNJh/JT1d+MhzqBvxz0MZ1GV4nqKfLtXK0mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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