SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '998376aaaf677898ab0e3cea6b1c90284dd82e1f90717d8200026b21cd54fd23' 
  AND token = 'CevKHf2gzjw5wEzVThW4U/xx5rpyFiLamIYRwg17q4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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