SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3471d1ed63cc9512e737c832d3807d6695a685d46491787559d9b6bc9425908f' 
  AND token = 'zCThV9uLpi+YiyZ0uD8E0rzHQOVFNPDzHKIUMBdVujk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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