SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35bfa0dc25c98f5dec522b8765dcad860ac264e16b56dd4258e302a1ae67ff5a' 
  AND token = 'UdbGLhp7cEFlBggVhLtOIfV0WPxTB6HzojHZIovpfHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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