SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3ec541ce3e3a1aa93a33bf371f03a8fe5fce617ed5a9d094625f65106dcd1b6' 
  AND token = '4lw5xNwOW0Oh5FVBsrhmHe3sKhJcgXs6SjrKnLAkScI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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