SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a443fef404c6851419c0c6eed80dce0e6791f638f407b6cb7c7d256a96895b' 
  AND token = 'qSgDhONbSNBiEZnPB5GuEOwA5jcEkHd5Prj9BzFbb44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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