SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37d9e403f7930d159eeadecd7f65ede5318061a09f9d3b294aa56fe31adfbb05' 
  AND token = 'FE5nJd7fd9LIFzoy9IDwOj9HscfRb0ht6+gphXIhgIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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