SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758befe904d5a2ec0a7321c5c2da6eedc19cdeaa03054b768a3a03dc715aaac2' 
  AND token = 'E52iJNfqzSQuuzn7VbyQvXSkXv6/oHJxoyn7DUQgSkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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